Mark,
It has been discussed at great length in past threads, but at the risk of getting back into that morass, I'll try to briefly explain it.
There are at least two different ways to look at it. One way is to look at the characteristics of a individual balls hit a different swing speeds. The USGA took this approach in a 2006 study where they looked at the distance characteristics of five different brands of tour balls at swing speeds between 90 and 125 mph. Results were slightly different between each ball, but generally and approximately: Between 90 and 100, the mechanical golfer picked up just over 3 yards for each additional mph club head speed. Between 100 and 110; the mechanical golfer picked up just a bit less, about 3 yards per mph; and between 110-120 mph, the hitting machine picked up around 2.5 yards or a bit less per one mph increase. (Another way to look at this, is for each decrease in mph, the lower swing golfer lost more yardage than the big hitter.) This is what I referred to when I mentioned diminishing returns at high swing speeds.
A second approach (and I think more useful approach) is to consider how much the new technology benefited various players at different swing speeds as compared to the previous state of the art technology. Unfortunately, we don't have a clean study for this one, but if we did, we would look at how much the slow swinging golfer gained (or lost) from the new technology, compared to how much the fast swinger gained from the new technology. Take the Pro V1x, for example. My hypothesis is that a golfer with a slow club head speed (say 80 mph) wouldn't gain much of any yardage with a Pro V1x as compared to previous technology, and he/she might even lose yardage. On the other hand, a golfer with a high swing speed (say 120 mph) would gain a bunch, maybe 30 or 40 yards or more. This is what I think most golfers were trying to express when they noticed that the fast swingers seemed to "unlock" the extra distance with these new balls- they seemed to get a bigger jump as compared to the old technology. There is nothing magical about these balls, its just that they don't seem to work any better for average golfers than did the old balls.
As for data, there is the 2006 USGA study by Quintivalla, but I don't know if it is still on accessible on the USGA website. There are also lots of attempts by others to try to quantify the differences between the old balls and the new balls, some of which have been discussed in this thread, and all of which have some potential shortcomings.
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Sean,
While there have been a series of jumps in distance brought on by technology over the past 100 years or so, this latest jump is by far the largest in history, at least for the longer hitters. Regardless, if you can figure out a way to get clubs and developers to "seek an alternative solution to courses being altered to accommodate equipment," then I am all ears. But so far as I can tell, over the history of golf, courses have been lengthened to accommodate the changes in distance brought on by technology, and so far as I can tell that is continuing today.
I haven't done a formal study (nor do I intend to) but I have looked at how and when course lengths have been increased over the years, and I continue to do so. While it would be impossible to prove direct causation, there seems to be a definite correlation between timing of jumps in distance brought on by new technology, and the the lengthening of courses. For example, the old literature in the early part of last century is full of examples of courses that were lengthened/changed and the reason most often given was that they had become outdated because of the haskell ball.
As for what would have happened if technology hadn't advanced since then, it is impossible to say. But having played with some of the old equipment, I cannot imagine that course builders would be building many 7500 yard courses if modern golfers were still playing with hickories and haskells.
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Garland, go back and look at these conversations from around 2000 and you will see the same arguments were being made then. Supposedly we were just at the limits of physics and there would be no more big jumps. Then came the big jumps in 2001 and again in 2003. We haven't had a big jump since, but I'll be surprised if we've seen the last one. Even if we are at the limit (which I doubt) the courses are already screwed as it is.