What Would the Ball Look Like Post Rollback or Bifurcation?

[Garland Bayley]

...
Clearly Ryan Moore has been listening to Garland too much and doesn't really understand the vagaries of trying to roll back the spin-rates to balata days.   

What are the vagaries? In the past I recall you indicated the difficulty to test to the standard. I have never understood, given modern technology, why it would be so difficult. Seems it would be easier than testing initial velocity when that standard was put in place.

[Bryan Izatt]

...
Clearly Ryan Moore has been listening to Garland too much and doesn't really understand the vagaries of trying to roll back the spin-rates to balata days.   

What are the vagaries? In the past I recall you indicated the difficulty to test to the standard. I have never understood, given modern technology, why it would be so difficult. Seems it would be easier than testing initial velocity when that standard was put in place.

It's not so much testing balls against the standard; it's establishing the standard and the test conditions.


First you'd need to establish the minimum spin rate that you wanted as your standard. How do you know what spin rate will bring distance down by some percentage? Presumably you want the standard to apply to the driver?  What loft of driver would you use to test the ball?  What angle of attack?  What swing speed?  What launch angle? What spin loft?


Then, how do you propose to prevent the elite golfers from transforming their driver set ups and swings to achieve spin rates below the minimum spin rate standard?

[Kalen Braley]

Bryan,


This is why they invented iron bryon.  Sure you can do the math and all that, but is it really that hard to say "hey guys lets take a break after a few tweaks and head over to the range and take some real world measurements."  Educated guessing coupled with Trial and Error is OK...nearly 20 years in tech tells me everyone does it far more than they will admit to.


Most of these posts are making ball roll back sound like its 1960 and we're trying to put a man on the moon, when in reality its much closer to 2018 and you're putting in a destination on Google Maps in your phone to get to LA.  Its not that hard and distance control doesn't have to be that exact.  Is 15-20% distance reduction for most PGA players really too general of a target?

[Erik J. Barzeski]

Is 15-20% distance reduction for most PGA players really too general of a target?

20%, sheesh. The PGA Tour wants no part of Dustin Johnson "bombing" it out there 245.

[John Kavanaugh]

Is 15-20% distance reduction for most PGA players really too general of a target?

20%, sheesh. The PGA Tour wants no part of Dustin Johnson "bombing" it out there 245.

It would only lead to even bigger, stronger, dumber looking golfers who could hit it 300. Does anyone really want to see Gronk in a pair of Sansabelts a half size to small.

[Kalen Braley]

Is 15-20% distance reduction for most PGA players really too general of a target?

20%, sheesh. The PGA Tour wants no part of Dustin Johnson "bombing" it out there 245.

Erik


He regularly hits it 340ish with roll. At 20% thats still 272 and at 15% 289.

P.S.  Those official driving averages are BS because they don't have to hit driver a lot of the time...

[Erik J. Barzeski]

He regularly hits it 340ish with roll. At 20% thats still 272 and at 15% 289.

P.S.  Those official driving averages are BS because they don't have to hit driver a lot of the time...

I don't know that I agree with your definition of "regularly." Nor do you know what percentage of the time for the stat he hits a 3-wood. I think they're more accurate than you seem to.

Doesn't change my point: the PGA Tour will almost certainly not support a roll-back.

[Garland Bayley]

...
Clearly Ryan Moore has been listening to Garland too much and doesn't really understand the vagaries of trying to roll back the spin-rates to balata days.   

What are the vagaries? In the past I recall you indicated the difficulty to test to the standard. I have never understood, given modern technology, why it would be so difficult. Seems it would be easier than testing initial velocity when that standard was put in place.

It's not so much testing balls against the standard; it's establishing the standard and the test conditions.


First you'd need to establish the minimum spin rate that you wanted as your standard. How do you know what spin rate will bring distance down by some percentage? Presumably you want the standard to apply to the driver?  What loft of driver would you use to test the ball?  What angle of attack?  What swing speed?  What launch angle? What spin loft?


Then, how do you propose to prevent the elite golfers from transforming their driver set ups and swings to achieve spin rates below the minimum spin rate standard?

There is no minimum spin rate! The slope limitation determines what the minimum and maximum will be through the set. The balata balls spun highly off of driver. The two piece balls spun lowly off of driver. There could be a whole continuum of ball spins, and the golfer is free to choose the one that works best for his game.

The pros would probably pick the balls that spun high off the high lofted clubs, i.e., analogous to wound balata, the rank amateur with high clubhead speed would probably choose the balls that spun low off the driver. Others would find what worked for them within the continuum.

The pros could optimize all they want, and that probably bring them back to the old days of low lofted drivers. The introduction of the ProV style balls allowed everyone to raise the loft on their drivers. When you optimize your driver to 5 degrees of loft, you suddenly have a big problem. Side spin is going to affect your result much more than it did from a 10 degree driver. Who knows what the true lofts of drivers are these days. Golf magazines keep saying that none of the manufacturers are honest about the loft, because they know no man wants to admit he is hitting a 12 degree driver, so the manufacturer marks it 10.5 instead.

Once side spin is competing with back spin for control of the ball, you lose the effect that "the long hitters aren't scared anymore. They just absolutely unleash on the ball now."

[Bryan Izatt]

He regularly hits it 340ish with roll. At 20% thats still 272 and at 15% 289.

P.S.  Those official driving averages are BS because they don't have to hit driver a lot of the time...

I don't know that I agree with your definition of "regularly." Nor do you know what percentage of the time for the stat he hits a 3-wood. I think they're more accurate than you seem to.

Doesn't change my point: the PGA Tour will almost certainly not support a roll-back.

Kalen,


On the designated pair of measured driving holes they do use driver most of the time.  Look to page 15 in the report below for the precise stats.


https://www.usga.org/content/dam/usga/pdf/2018/2017-distance-report-final.pdf

[Thomas Dai]

I recently found a couple of Titleist 'Professional' balls from circa the late 1990's.
Soft, spinny, can balloon, swerves a good deal on a poor strike yet pretty durable by previous balata standards. Not as long as what's now standard. Would be a great ball to roll-back too (especially if coupled with persimmon! ).
atb

[Bill Gayne]

I don't know what a "post rollback or bifurcation ball" looks like but if you could do it the results would allow for a shorter course. Combine the shorter course with taking a couple of steps back on green speeds and the time to play a tour round could be reduced. Add in enforcement of pace of play rules. Eventually the culture of slow play on tour may change. Yesterday's five hour and forty minute rounds were about an hour and forty minutes too long.

[Garland Bayley]

I don't know what a "post rollback or bifurcation ball" looks like but if you could do it the results would allow for a shorter course. Combine the shorter course with taking a couple of steps back on green speeds and the time to play a tour round could be reduced. Add in enforcement of pace of play rules. Eventually the culture of slow play on tour may change. Yesterday's five hour and forty minute rounds were about an hour and forty minutes too long.

Must be a typo. I'm sure you meant two hours and forty minutes too long. And that was still an hour too long for some of competitors.

[Bryan Izatt]

...
Clearly Ryan Moore has been listening to Garland too much and doesn't really understand the vagaries of trying to roll back the spin-rates to balata days.   

What are the vagaries? In the past I recall you indicated the difficulty to test to the standard. I have never understood, given modern technology, why it would be so difficult. Seems it would be easier than testing initial velocity when that standard was put in place.

It's not so much testing balls against the standard; it's establishing the standard and the test conditions.


First you'd need to establish the minimum spin rate that you wanted as your standard. How do you know what spin rate will bring distance down by some percentage? Presumably you want the standard to apply to the driver?  What loft of driver would you use to test the ball?  What angle of attack?  What swing speed?  What launch angle? What spin loft?


Then, how do you propose to prevent the elite golfers from transforming their driver set ups and swings to achieve spin rates below the minimum spin rate standard?

There is no minimum spin rate! The slope limitation determines what the minimum and maximum will be through the set. The balata balls spun highly off of driver. The two piece balls spun lowly off of driver. There could be a whole continuum of ball spins, and the golfer is free to choose the one that works best for his game.

The pros would probably pick the balls that spun high off the high lofted clubs, i.e., analogous to wound balata, the rank amateur with high clubhead speed would probably choose the balls that spun low off the driver. Others would find what worked for them within the continuum.

The pros could optimize all they want, and that probably bring them back to the old days of low lofted drivers. The introduction of the ProV style balls allowed everyone to raise the loft on their drivers. When you optimize your driver to 5 degrees of loft, you suddenly have a big problem. Side spin is going to affect your result much more than it did from a 10 degree driver. Who knows what the true lofts of drivers are these days. Golf magazines keep saying that none of the manufacturers are honest about the loft, because they know no man wants to admit he is hitting a 12 degree driver, so the manufacturer marks it 10.5 instead.

Once side spin is competing with back spin for control of the ball, you lose the effect that "the long hitters aren't scared anymore. They just absolutely unleash on the ball now."

Just to make sure that I've got your proposal correct, you want to regulate the slope of linear relationship between spin rate and loft.  For the sake of discussion, you would regulate that a ball must spin 400 rpm more for each degree of loft added.  So a ball that spins at 2000 rpm off a 10° driver (under some set of club and swing parameters) would be required to spin 10000 rpm off a 50° wedge.  And for 3000 off the driver it'd have to be 11000 off the wedge, and say 4000 and 12000. 

What slope do you suppose you would propose for the regulation?

At what driver spin rate do you suppose there would be measurable distance reduction?

Or, are you just trying to increase the driver spin to make drives more errant for elite golfers in the hopes they'll dial back their swing speed for better control?

Do you think that a difference of 1000 or 2000 rpm in wedge spin would incent the pros to choose a higher spinning ball?

You know that the static loft printed on the driver, whatever it is, is kind of irrelevant, don't you?  What's important to spin is the spin loft.  It is a function of the static loft, the club and the swing.

You also know, don't you, that there is no such thing as side spin competing with backspin?  There is only spin around the spin axis.  Tilting the spin axis results in draws, hooks, fades and slices.  The tilt of the spin axis depends on the difference between the face direction and the swing path direction at impact.

Do you have any idea how many yards pro golfers will lose in distance or will increase in yards of lateral deviation if they chose a ball that spun at 3000 or 4000 rpms off of a driver?

So, you could write the regulation, establish a set of test parameters for drivers and wedges, and devise a test protocol with an iron byron, but before that you'd need to understand what goal your trying to achieve.  If it's to make the ball more erratic for pro golfers, it seems kind of complicated.  It'd be easier to make the ball lighter or bigger.  If you want to increase spin to reduce distance you'd need to fully understand how much difference you'd need to have to get the desired difference in distance.  That also seems complicated and, to me, easily worked around by elite players by adjusting their swings.

It'd be easier in all respects to make the ball bigger or lighter or with a lower COR or some combination of the above.  Easier to write a regulation, easier to test, and harder to work around.  But you can continue to spin about spin.
 

[Bryan Izatt]

And, here for those interested in the difference between a current Pro V1 and a 1998 Titleist Professional is a link to a You-tube video of a comparison by Rick Shiels between the two using driver, 7 iron and wedge.  You can skip the ad after a few seconds.


https://www.youtube.com/watch?v=x6B6U0DflaY


Vis-a-vis the spin discussion, it is interesting to note that the modern Pro V1 actually spins slightly more off the wedge.  More interesting is that the Pro V1 doesn't spin any less off the driver.  The facts seem to contradict our past perceptions of the spin of the Professional ball.


There was little difference in the wedge distances and about 11 yards in carry distance with the driver.  There is no mention of weighing the Professional, but based on my personal experience there is probably a loss of 4 or 5 grams due to aging.  That would probably make the ball less resilient after 20 years.


The results are not much different from what I have seen in my own test in a sim with an old Professional that I have.  Shiels test is more rigorous than mine with better equipment for measuring the results.  And, of course, he swings much faster and hits it on the sweet spot more often than I do.   


     

[Garland Bayley]

Just to make sure that I've got your proposal correct, you want to regulate the slope of linear relationship between spin rate and loft. 

Correct

For the sake of discussion, you would regulate that a ball must spin 400 rpm more for each degree of loft added.  So a ball that spins at 2000 rpm off a 10° driver (under some set of club and swing parameters) would be required to spin 10000 rpm off a 50° wedge.  And for 3000 off the driver it'd have to be 11000 off the wedge, and say 4000 and 12000. 

There is no driver. There is no wedge. There is just a clubface like surface that balls are fired at, and resultant spin measured.

What slope do you suppose you would propose for the regulation?

The slope given by the two piece balls in the 1990 study would be a good starting point to consider.

At what driver spin rate do you suppose there would be measurable distance reduction?

Or, are you just trying to increase the driver spin to make drives more errant for elite golfers in the hopes they'll dial back their swing speed for better control?

The goal is to return spin characteristics back to where they were before the highly engineered ball increased the spin/loft slope circa year 2000. Before year 2000 elite golfers were not swinging as hard. However, the popularity of the PGA Tour was exploding. It would seem to me that the long ball has little to do with the popularity of professional golf.

Do you think that a difference of 1000 or 2000 rpm in wedge spin would incent the pros to choose a higher spinning ball?

I don't have to think. It was already the practice. Just reinstate the previous characteristics and I see no reason why they would not return to using the higher spinning ball. To score they need short game control. They could care less about how far they hit it, because they are all in the same boat, and tees would be returned to where they were.

You know that the static loft printed on the driver, whatever it is, is kind of irrelevant, don't you?  What's important to spin is the spin loft.  It is a function of the static loft, the club and the swing.

Of course static loft printed on the driver is irrelevant to the test proposed. In the materials I read, what you call spin loft is probably referred to as effective loft.

You also know, don't you, that there is no such thing as side spin competing with backspin? 

That is just a terminology that I have seen golfers and golf teachers using.

There is only spin around the spin axis. 

That of course is how the scientists refer to the same thing.

Tilting the spin axis results in draws, hooks, fades and slices.  The tilt of the spin axis depends on the difference between the face direction and the swing path direction at impact.

Do you have any idea how many yards pro golfers will lose in distance or will increase in yards of lateral deviation if they chose a ball that spun at 3000 or 4000 rpms off of a driver?

I have no clear idea. That is not the goal. The goal is to return to the state it was for instance when Tiger joined the tour in 1996 I believe.

So, you could write the regulation, establish a set of test parameters for drivers and wedges, and devise a test protocol with an iron byron, but before that you'd need to understand what goal your trying to achieve.

None of that is pertinent.

If it's to make the ball more erratic for pro golfers, it seems kind of complicated.  It'd be easier to make the ball lighter or bigger.  If you want to increase spin to reduce distance you'd need to fully understand how much difference you'd need to have to get the desired difference in distance. 

I already know how to get the desired difference in distance. Return the ball to the previous state.

That also seems complicated and, to me, easily worked around by elite players by adjusting their swings.

The can adjust their swings all they want. Unless the human biomechanics have evolved significantly in a few years as opposed to the many generations one expect would be required for that evolution, they will find they are in the same boat they were all in when Tiger upset the apple cart.

It'd be easier in all respects to make the ball bigger or lighter or with a lower COR or some combination of the above.

The invention of the new ball that upset the apple cart after more than half a century wasn't easy. If they can do that, they can probably disinvent it. I would suggest a relatively thick soft balata cover around a solid core that accurately reflects the behavior of a wound core.

Easier to write a regulation, easier to test, and harder to work around.

And further remove the game from what it has been.
 
But you can continue to spin about spin.

C'est la vie.

[Bryan Izatt]

The goal is to return spin characteristics back to where they were before the highly engineered ball increased the spin/loft slope circa year 2000.

Just reinstate the previous characteristics ..............

The goal is to return to the state it was for instance when Tiger joined the tour in 1996 I believe.

Re point 1 above, the Lieberman and Trackman graph seems to show that the current spin/loft slope has been decreased, not increased, relative to the balata and 2-piece balls of yore.  Do you have data that shows otherwise?

Re point 2, what characteristics?  Just the spin/loft slope of Lieberman?  Or, some other characteristics - balata covers, dimple patterns, liquid cores? 

Re point 3, what was that "state" - the pros didn't hit it so far or so straight or score so low?

Did you watch the Shiel video?  Seems pretty convincing that there isn't much difference in spin-rates or spin/loft ratio between the Professional and the Pro V1.

[Garland Bayley]

Bryan,

I don't know if you have seen this, but in case you haven't, you might want to take a look at
https://www.andrewricegolf.com/andrew-rice-golf/2011/08/evolution-of-a-golf-ball

[Garland Bayley]

...
I put the spin-rates for the balata ball and the 2-piece ball on the same chart as the Trackman PGA Tour players as shown below.  You might notice that the 2-piece ball line actually gets closer to the balata ball at the higher lofts.  The lines are not really parallel.
...

I would point out that these two sets of data in no way belong on the same graph. They were collected under very different circumstances, so there is almost nothing to be learned from the graph.

[Garland Bayley]

Bryan,

I occurs to me that a ball to test vs. surlyn two piece balls would be the Bridgestone E5, a two piece urethane covered ball. Unfortunately, I went to the Bridgestone golf website, and they seem to have dropped that ball. I have to wonder why. I recollect Golf Digest tests showing it had wedge spin nearing the three piece balls.

EDIT: I just found a Golf Digest statement that the E5 spins more off the driver. It seems as I suspected, the ball was targeted to older or slower swinging players where the added spin from driver could be helpful.

[Garland Bayley]

http://raypenner.com/golf-physics.pdf

Reports the Lieberman article. I don't have a link to the original.
The methodology was to fire balls at an angled surface and measure the resulting spin.
Grooves are totally uninteresting, as the contribute nothing in controlled experiments measuring impact spin. Their purpose is to remove grass and water from the impact.

Thanks for the link.  So, you're putting forth second hand information that has no context as proof of your theory.

Referring to this as second hand information does not convey the status of the information. A scholarly paper is going to be reviewed before publication and that would limit false information from being propagated.

The Lieberman paper is about the effect of grassy vs dry impact conditions on spin-rate.

Were you able to get a copy of the paper to read? If so, can you share offline? I just put in an interlibrary loan request for the book.

One conclusion was that the spin rate was higher with grassy conditions for lower loft angles (say middle irons down).  Your linked article does not say what the conditions were for the spin-rates provided - was the plate dry or grassy;

It seems to me they would have to do both to determine higher spin rate with grassy conditions.

what ball speed was used.  It was also a lab test firing balls at a angled plate and using high speed photography to capture the spin-rate, so not really similar to tour players hitting actual clubs and using Trackman to get the spin. Never-the-less I don't think theses numbers tell the story you want.

I think they do. I am not too concerned with results hitting balls with clubs and results captured on Trackman.
...

[Garland Bayley]

The characteristics and state referred to in my earlier answer that you ask about are the characteristics of the two balls tested in the 1990 paper, and the state of those balls reaction to being hit by PGA Tour pros in tournaments.

In 2001 tour driving distance jumped 6.2 yards. I suspect this jump would revert. Clearly there are other things that have caused distance to increase like club length, club weight, driver head size, driver COR, but changes there would have been more distributed through time. Perhaps they could have contributed about 1 yard that year, but the change in spin clearly dominated this result.

In 2003 tour driving distance jumped 6.5 yards. I suspect some of this jump would revert. I believe this jump resulted from players learning to optimize conditions with the new ball. Even though technology was not available for optimization before, I strongly suspect that players were semi-optimized by finding what worked best for them in the earlier era. I doubt optimizing with a rolled back spin ball would allow players to maintain this full gain.

[Bryan Izatt]

Bryan,

I don't know if you have seen this, but in case you haven't, you might want to take a look at
https://www.andrewricegolf.com/andrew-rice-golf/2011/08/evolution-of-a-golf-ball

Yes, I had seen the Andrew Rice article before.  The takeaway from a spin point of view is that there is little difference in spin off the driver for Titleist Balata, Professional, ProV1 392 and the 2011 Pro V1.  I think that finding, along with the Shiel test which shows the same thing would be counter-intuitive for most people.  But, the data is what it is.


As for the chart, sure, the two sets of data were completely different methodologies, but I think the result is indicative.  It doesn't jive with your preconception so you want to throw it out, but I think it is indicative.


To muddle your mind further, I've added the three data points for the Professional and the ProV1 from the Shiel test to the chart.  The two have very similar slope and are not too different from the Trackman Tour average line.  And, the methodologies are similar.


Worth noting is that Shiel has a higher slope than the Tour average.  I guess his swing generates more spin with the wedge than the average.  I'd be willing to consider other data if you have some.







Re the E5, urethane covered balls are supposed to spin more than surlyn covered balls.  I'm sure you must have seen these Golf Digest spin charts from years past.  The E5 is up there in spin.

[Bryan Izatt]

The characteristics and state referred to in my earlier answer that you ask about are the characteristics of the two balls tested in the 1990 paper, and the state of those balls reaction to being hit by PGA Tour pros in tournaments.

In 2001 tour driving distance jumped 6.2 yards. I suspect this jump would revert. Clearly there are other things that have caused distance to increase like club length, club weight, driver head size, driver COR, but changes there would have been more distributed through time. Perhaps they could have contributed about 1 yard that year, but the change in spin clearly dominated this result.

In 2003 tour driving distance jumped 6.5 yards. I suspect some of this jump would revert. I believe this jump resulted from players learning to optimize conditions with the new ball. Even though technology was not available for optimization before, I strongly suspect that players were semi-optimized by finding what worked best for them in the earlier era. I doubt optimizing with a rolled back spin ball would allow players to maintain this full gain.

Re the Lieberman article, no I didn't find the whole article, just some snippets from Google books. Do share when you get the whole article.


I still don't get what specifically you mean by "characteristics" and "state".  Do you mean that you want modern balls to match the slope of the Lieberman line when fired at an angled metal plate, under whatever test conditions Lieberman had.  Would you allow them to have a greater slope of less slope or do they need to have exactly the same slope?  I think you'll find that Lieberman found that the slope varied depending on whether the plate was dry or grassy.  Do you want to factor in real world conditions in your slope.


I still don't understand how you think regulating the spin slope will affect distance or accuracy for professional players.  What do you think would happen if a player opted for a higher spin ball for short game control?


As for using year-to-year changes in PGA Tour distances you forgot to include other factors that probably contributed to those year-to-year changes - some of the players changed; some of the courses changed; and, course conditions changed due to weather.  Not to  argue that the ball had nothing to do with the distance gains in that time period.  Obviously they did, but there were a lot of other factors involved too.  It presents a very complicated cause and effect analysis.  I think that spin is a lot smaller factor than many others.

[Garland Bayley]

...
As for the chart, sure, the two sets of data were completely different methodologies, but I think the result is indicative.  It doesn't jive with your preconception so you want to throw it out, but I think it is indicative.
...

Indicative of what? The addition of the Shiel data shows the slope for the ProV1 is steeper than for the Professional. Exactly my thesis.
Any other matching is meaningless. You don't know the conditions of the Lieberman data for low loft, or for high loft. So matching low loft points is meaningless. Matching high loft points is meaningless. The Lieberman data would simulate equal club head speed for all, whereas the other data has high club head speed for low loft, and low club head speed for high loft.

[Garland Bayley]

Re the Lieberman article, no I didn't find the whole article, just some snippets from Google books. Do share when you get the whole article.


I still don't get what specifically you mean by "characteristics" and "state".  Do you mean that you want modern balls to match the slope of the Lieberman line when fired at an angled metal plate, under whatever test conditions Lieberman had. 

Yes

Would you allow them to have a greater slope of less slope or do they need to have exactly the same slope?

USGA regulations always have a fudge factor around a reasonable bound. Something along those lines would have to be worked out.

I think you'll find that Lieberman found that the slope varied depending on whether the plate was dry or grassy.  Do you want to factor in real world conditions in your slope.

USGA regulations try to avoid real world conditions. They did away with Iron Byron hitting balls outdoors,
because they couldn't control real world conditions (weather). Besides, the USGA has already worked on the grassy club face issue with their groove regulations.


I still don't understand how you think regulating the spin slope will affect distance or accuracy for professional players.

Clearly optimizing spin allows you to hit the ball farther. I believe that when you optimize a higher spinning ball, you have to reduce the effective loft of the club during contact. When you reduce the loft, the force component for applying back spin will decrease. The force component applying side spin will stay the same. The axis of spin will shift. The ball will curve more. Besides, that is essentially what many tour pros have indicated in layman's terms.
 E.g., the Ryan Moore's comment doesn't say that, but I believe it implies that he believes players would have to dial back their swings with a ball that spun like the wound balata balls. My own experience is hitting TopFlites 300 yards with a 2 wood in the early 70s, while seeing Titleists balloon up and fall short. Couldn't control the Titleists with a driver without dialing the swing back. At the time I was a highly conditioned college BBall player that spent 8 hours a day during the summer tossing heavy lumber around in a sawmill so I had very strong wrists and forearms.
 
What do you think would happen if a player opted for a higher spin ball for short game control?


As for using year-to-year changes in PGA Tour distances you forgot to include other factors that probably contributed to those year-to-year changes - some of the players changed; some of the courses changed; and, course conditions changed due to weather.  Not to  argue that the ball had nothing to do with the distance gains in that time period.  Obviously they did, but there were a lot of other factors involved too.  It presents a very complicated cause and effect analysis. 

Plot the gains before, and the gains after. You will probably find a small component that can be contributed to all the other factors. I believe the discrete jumps that happened at the event of introduction of the new ball, and optimization with the new ball will clearly dominate the results you see.

I think that spin is a lot smaller factor than many others.

I disagree.