Bandon Trails Slope

[Tom Huckaby]

Jeff:

True.  But remember from 170 he also has a CHANCE of getting it on the green.  By definition also in course rating, the bogey golfer doesn't tend to play very smart - he lays up by choice only very very infrequently.  So at 200, he's smacking all he can... and that can get into a lot of trouble as well, even if he doesn't reach the defined hazards.

For me it comes down to this:  from 170, he has a chance to make a few pars.  From 200 he will make basically none.   The question is do his "others" achieved from 170 - because he reaches the hazards - outweigh the number of pars he'll make from that distance?  And can we assume also he always makes 5 at most from 200?  More distance means more room to screw up.... It's far from a fair assumption to say he gets every shot to 30 yards and then simply pitches on....

Thus my questions.  For course rating purposes, it's clear his target ratings coming from 200 (which will actually be 30) will be a lot lower than those coming from 170.  But in the end does this equate to total less strokes?  Not really... and thus this gets pretty darn interesting.

TH

[JohnV]

Jeff, he also has a better chance of saving par from just short rather than a greenside bunker or on a steep mound to the side of the green.  Also, the area in front of many greens is frequently flat and at green level, while 165 yards out it might be on a slope and 10 or 15 feet below the green where you can't see the surface (this affects both topography and green target.)

[Tom Huckaby]

Jeff, he also has a better chance of saving par from just short rather than a greenside bunker or on a steep mound to the side of the green.  Also, the area in front of many greens is frequently flat and at green level, while 165 yards out it might be on a slope and 10 or 15 feet below the green where you can't see the surface (this affects both topography and green target.)

JV - we crossed - that's all true, but my questions remain.   I just can't get over thinking about this in terms of total strokes.


Brass tacks:  would a series of 2 ratings on 3rd shots really make for an easier golf course than a series of 7 ratings on 2nd shots?

That's what I can't get a good grasp on.

TH

[JohnV]

Tom, that is why the Bogey Rating does go up and why it is so unusual for the slope to go down.  I can't say whether the OGA is being brave or stupid in their ratings as I know of few other associations who are willing to put out numbers like that.  There is some leeway in the numbers that the person in charge of calculating the course rating can change things a few tenths on the rating and a point or two on the slope and I'd bet that some do it to avoid this situation.

Imagine a hole with a water hazard immediately to the right of the green.  If the bogey golfer is 160 yards out, he is going to hit into it a lot.  If he is 195 out and can't reach it, he isn't.  He'll probably save par about 1/4 of the time from 25 yards short of the green.  He almost never will from the water.

A series of 2 ratings would make the obstacle factors lower than the series of 7 ratings, but the yardage would more than make up for it so the overall rating would go up.

I could probably design a couple of very absurd sets of yardages where this might not be true, but it would be too weird to happen.

[Tom Huckaby]

EUREKA!

JV, that makes great sense to me - thanks.  And apologies for being slow on the uptake.  This is a weird situation for sure - but oddities like this make for great conversation before and after the rating process.

 

[Jim Nugent]

Surprised Cary didn't chime in here.

He has written he scores better from the back tees at TPC than the forward ones, because the hazards are taken out of play then. In JVB's terms "the obstacle ratings went down"

Garland -- isn't Cary pretty close to scratch?  If so, and his experience is typical, course rating should fall from the tips there.  Anyone know if that ever happens?    

[JohnV]

Jim,

That is extremely unlikely since the yardage will usually make it go up.  Notice that the Bandon Trails Bogey Rating went up, just not as much as the Course Rating did which caused the Slope to go down.

Yardage is still the predominant factor in rating so any increase would probably overwhelm any lowering of the obstacle numbers.

[Garland Bayley]

Surprised Cary didn't chime in here.

He has written he scores better from the back tees at TPC than the forward ones, because the hazards are taken out of play then. In JVB's terms "the obstacle ratings went down"

Garland -- isn't Cary pretty close to scratch?  If so, and his experience is typical, course rating should fall from the tips there.  Anyone know if that ever happens?    

Yes I forgot about that.

So near scratch and short (can't reach the hazards) makes for easier.

It just goes to show that all of these are based on averages and do not fit everyone. The long hitting high handicapper is perhaps going to clear hazards at Bandon Trails from the handicap "appropriate" tees and score better than normal. When he goes back to the lower slope rated back tees, perhaps that will then bring the hazards into play and he will score much worse.

Which brings up the question, how scientific is the course rating procedure. Was it developed empircally?

[Dave Kemp]

Interesting discussion especially having just finished my first rating training seminar.  I am going out Friday to shadow a team on a new course for the first time.

One quick question for JV ; how were you able to discern the split between yardage and obstacle rating for CR and BCR from the published slope and rating for BT?  Is there a set percentage assigned to each and once you know the CR (or BCR) you can determine the split?

As for courses advertising their slope I remember seeing a guy wearing a ball cap from his course with the slope embroidered on the side.  At the time I was impressed not knowing what I do now about what it actually means.  

[Tom Huckaby]

Dave - welcome to the brotherhood.  Just understand as a course rater you don't HAVE to know all the esoteric stuff discussed in this thread - you just have to get to know how to do a rating.  Watch the other guys, talk to the experienced ones, they'll show you how.    

As for your question to JV - I answer because he has a life and I'm never sure if he's gonna get to these questions... so take my answer with a grain of salt... but I think there's IS a  standard formula for what distance equates to in course rating, with no obstacle addition at all... call that yardage rating... So JV knowing that and all the other data could just figure the obstacle additions for each set of tees and each golfer.

Putting slope on a cap... that's a new one but it doesn't surprise me.  It's also pretty sad.  

[JohnV]

One quick question for JV ; how were you able to discern the split between yardage and obstacle rating for CR and BCR from the published slope and rating for BT?  Is there a set percentage assigned to each and once you know the CR (or BCR) you can determine the split?

As I said at the top of my first post, I don't know the exact numbers, I'm just going by the standard formula.

The basic formulas are:

ScratchYardageRating = ScratchEffectivePlayingLength/220 + 40.9
BogeyYardageRating = BogeyEffectivePlayingLength/160 + 50.7

CourseRating = ScratchYardageRating + ScratchObstacleStrokeValue
BogeyCourseRating = BogeyYardageRating + BogeyObstacleStrokeValue

Slope = (BogeyCourseRating - CourseRating) * 5.381

Since I don't know the real value for either of the Effective Playing Lengths above, I used the card yardages.  They are probably different from that which makes all the obstacle values approximations also.  If you remember your basic algebra, you can work backwards to figure out the rest of the numbers I gave.

Things which modify the measured yardage to create the Effective Playing Lengths are: Roll (firm plays shorter), Elevation from tee to green, Doglegs or Forced Layups, Prevailing Wind and Altitude.  Altitude has no effect at Bandon, Prevailing Wind could, but I'm not sure they would use it for a course that is somewhat inland such as the Trails.  I was on the first rating time for Bandon Dunes and we did use it then.  Doglegs can lengthen or shorten the yardage depending on whether the player can't reach the corner or can play over the corner.  Forced Layups are for things like streams or lakes that cross a fairway.

[JohnV]

As a followup to the previous posting, you can see that for every 220 yards you add one to the Course Rating.  Adding 160 yards adds one to the Bogey Course Rating.  Likewise shortening the course.  So, when you go play a course and all the tees are 10 yards shorter than from where it was measured, which happens at a lot of courses on weekends, you are taking over one off the Bogey rating and nearly one off the Course rating.  This leads to handicap indexes that are too low for most players.

[Dave Kemp]

ScratchYardageRating = ScratchEffectivePlayingLength/220 + 40.9
BogeyYardageRating = BogeyEffectivePlayingLength/160 + 50.7



Thanks for the further explanation John.  The formulas I pasted from your message above are the ones I was not aware of.  I have now looked at my notes from my rating seminar and in them there is mention of the Obstacle Stroke Value.  If I understood the instructor right  11% of the CR value comes from OBS and 26% of the BCR from the OBS.  Does this make sense?

Tom, thanks for the words of encouragement.  I realize that the raters do not have to have a full understanding of this breakdown when gathering the data on course.  I always like to delve into things though; must be the engineer in me.  

[JohnV]

Dave, it would be a very strange course where that high a percentage came from the obstacle values.

For example, Bandon Trails from the back tee 2.3% of Course Rating and 3.7% of the rating is from the obstacles.  From the middle tee it is 2.1% and 7%.   These are making the same assumptions as above regarding playing length vs measured length.

Basically the obstacles make up 1-10% of the value.  But, they are important as they are the difference between a 6700 yard course with big greens and no hazards and a 6700 yard course with small greens and lots of hazards.

[Doug Siebert]

For me it comes down to this:  from 170, he has a chance to make a few pars.  From 200 he will make basically none.   The question is do his "others" achieved from 170 - because he reaches the hazards - outweigh the number of pars he'll make from that distance?  And can we assume also he always makes 5 at most from 200?  More distance means more room to screw up.... It's far from a fair assumption to say he gets every shot to 30 yards and then simply pitches on....

Think of it this way.  Let's say you are caddying for a bogey golfer in a match against another bogey golf with a $10,000 bet on the line, and you get 10% of it if he wins, so you have a big stake in the outcome.  It is a very repetitive course, so there are a lot of holes where he'll end up with a 170 yard approach, with bunkers and deep rough on mounds on both sides, but an open approach to roll the ball into the green.  He hits his 3W 170 yards, so a well hit and straight 3W should reach the middle of the green, where the pin is.

Do you hand him his 3W or do you encourage him to hit a 7W or hybrid short of the green to take those bunkers and rough encrusted mounds out of play, giving him a chance at a par and taking double out of play?

You ever read Tommy Armour's How to play your best golf all the time?  He relates a story about a guy who has never broken 90 and he bets someone else that he can get the guy to break 90 if he gets to tell him what club to use, where to aim, etc. on every shot.  So they play, and instead of letting the guy hit a 3W at a green just on the outside edge of his range he hands the guy an 8i to lay up, that sort of thing.  Guy ends up shooting a 79.

[Jim Nugent]

Doug, I remember reading that story from Armour's book.  I wonder if it actually happened, or is more like a parable to make a point?  

JVB and others: since we already have bogey and course ratings, why do we need slope?  

[Matt_Cohn]

A related question:

Harding Park is only rated from the 6,816 "back" tees (72.8, 126).

But the real back tees are 7,150.

So can I just add (7150-6816)/220=1.5-ish

...to get a course rating of 74.3? Or will the obstacle scores change from back there, too?

What's the new slope rating from 7,150?

(While we're at it, is it legal to post my handicap using the 74.3 number? Or do I have to post using 72.8?)

[JohnV]

Matt,

The USGA publishes a table on what to post for a set of unrated tees in their handicap system manual which can be found on their website.  The tables can be found in Section 5-2g.  For the tees you mentioned, with a difference of 334 yards, the Course Rating would go up 1.9 strokes and the slope 4 points.  If those are the usual tees, the club should get Tom Huckaby and his buddies at the NCGA to come out and re-rate the course from them.

Jim,

The purpose of slope is to standardize the way to convert the handicap index to a handicap and then to convert your score back to a handicap differential.  Without it, the calculations would be much more difficult and would require a separate table for every course rating/bogey rating combination.

Handicap = HandicapIndex * Slope / 113
113 is the slope of a course with standard difficulty

Replace Slope with (BogeyRating - CourseRating)*5.381 you see that it becomes more difficult to calculate.

Going the other way your differential that is used to calculate your HandicapIndex is:

Differential = Score * 113 / Slope

The golfer doesn't worry about this one, but it is more complicated without Slope.

The mistake was that the USGA didn't publicize the Bogey Ratings until a few years ago so everyone focused on Slope.

[Tiger_Bernhardt]

The amazing thing is I am finding this interesting as well. Thanks to the positive contributors.

[JohnV]

Matt, if you are playing from 7150, you should post the score with the changes I noted so it should be 74.7 and 130.

For all, using the table that I mentioned, you can play any combination of tees on a course and still post your score.  So, for all who like to mix and match tees, print out the table and go for it.

[Tom Huckaby]

Doug S.:

Aha!  Well here's where the disconnect is.  For course rating purposes, the assumption is the bogey golfer has NOT read Armour's book, nor does he play a game that's smart in any way shape or form.  No offense to you educated bogey golfers out there, but you have to understand you are in the minority.

Also your distances are off... for course rating purposes, he gets no more than 170 yards total from any non-tee shot.

In any case your explanation is fine for how a bogey golfer COULD shoot a better score from those longer distances... but that's not what I'm asking.  I get that.  I'm asking course rating questions here.




BTW to JV and Matt - my buddies did re-rate Harding, this past Friday.  Not sure if they did those 7150 tees... but that's up to the course to ask for, right?  That is, we only rate the tees they say are actually used.  And then among those, tees on any hole have to be 25 yards apart to get a separate rating.  Aren't those 7150 tees at Harding used only for the pro events?  And if so, it doesn't surprise me they didn't get a separate rating.  But maybe they caught that last Friday.  I was supposed to go, but life intervened.

TH

[Jim Nugent]

The purpose of slope is to standardize the way to convert the handicap index to a handicap and then to convert your score back to a handicap differential.  Without it, the calculations would be much more difficult and would require a separate table for every course rating/bogey rating combination.

Handicap = HandicapIndex * Slope / 113
113 is the slope of a course with standard difficulty

Replace Slope with (BogeyRating - CourseRating)*5.381 you see that it becomes more difficult to calculate.

Going the other way your differential that is used to calculate your HandicapIndex is:

Differential = Score * 113 / Slope

The golfer doesn't worry about this one, but it is more complicated without Slope.

The mistake was that the USGA didn't publicize the Bogey Ratings until a few years ago so everyone focused on Slope.

John, seems to me it is only a little more complicated.  Say we drop slope, and put (Bogey - Course Rating) x 5.381 in its place.  Then 5.381/113 = 0.04762, and the formula becomes:

Handicap = HI x (Bogey - CR) x 0.04762.  

There is one extra calculation.  But aren't handicaps usually figured by computers?  So what difference does it make?  In the meantime, Bogey rating seems to me more useful info than slope.

[JohnV]

Handicap Indexes are figured by computer.  When you get to a course, you can look up your index on the charts that are provided to the club to determine you handicap.  Also many associations provide booklets with the slope charts in them.  To do this without slope would require either a chart for every possible combination or at least one for every difference between CR and BR, which would then require the player to do the subtraction.  The minimum difference between CR and BR is 10.2 and maximum is 28.8 (slopes of 55 and 155).  It is possible to have numbers outside that range, but those are the min and max slopes allowable.

Slope is a simpler number for people to use, but it has caused confusion.  Education can solve that.  Different people have worked with golf writers and others to get them to understand this and most articles these days don't say that the highest slope is the hardest course, but rather that the highest course rating is.

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