Seriously, Bryan, I am not out to tar and feather anyone, but I do wish you were as intellectually rigorous with your own claims, anecdotes, and theories as you are with everyone else's.
You keep circling back to swing speed and athleticism as having played a large role in the increased distances. I don't deny that these things may have played some sort of role (especially as young players develop within this new equipment regime,) but I think you and others are dramatically overstating the significance of these variables in helping explain the changes over the relevant period. You never seem to accept my efforts to do so, but you are savvy enough with the numbers so that you could go into the data and (as best you can) try to control the swing speed and athleticism. If you do, I think you will see that the primary factor is indeed changing technology.
For example, go back and take a look at the distances gained by the golfers who switched to the ProV1x from 2002 to 2003. These numbers focus on individuals over a relatively short period of time and so the numbers ought to do a pretty decent job of controlling for swing speed, athleticism, and conditioning. Yet the huge gains are there, due to changing technology. For just one example, Ernie Els didn't suddenly become more athletic or drastically change his swing or get in much better condition between the last tournament in 2002 and the first tournament in 2003. But he did change his equipment, and when he changed his equipment he suddenly could hit the ball 20+ yards further.
Or take the Andrew Rice experiment. The same golfer on the same day with the same swing speed hit first generation of the ProV1x twenty-plus (20+) yards further on average than he did the first generation ProV1. That is technology and NOT a change in swing speed, athleticism, or conditioning. Or maybe I am wrong, but if so let's see the evidence . . .
At age 48, Fred Couple's club head speed was reportedly 118 mph. Do you really think that the newer golfers swing significantly faster now than 20 years ago?
Where are the studies indicating a significant increase in swing speed or athleticism has played a major role in the increased distances? Likewise, where is the study indicating that what you call the "likely fact" that the gap in swing speeds has increased? I understand the anecdotal appeal of such a claim, and there may be a grain of truth to it, but I simply don't buy that it is responsible for the magnitude of changes we have seen. Also, Bryan, keep in mind that swing speed and technology are very much related. Lighter shafts, better materials, less twisting, different, larger club heads. All theoretically allow a golfer to swing harder without adverse consequences. That is technology.
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I used to read that the tour swing speed was 110 mph on average. Now I read that it about 112 mph on average. According to the Quintavalla study, at those swing speeds with the tour balls, this increase in average swing speed would only be worth about 5 yards in distance gain, at most. In contrast, your chart shows a jump in yardage of over 30 yards.
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As for your hockey analogy, I understand your point but don't think it is a good fit to the situation in golf. For one thing, most of the change in golf has come from technology. For another this is the most important issue of how the golfers interact with the courses. In this regard, baseball might be a better metaphor. In professional baseball the players have obviously become bigger, faster, and stronger and some would argue more skilled. But because the implements are regulated the game still fits in the field of play, yet the players are still able to showcase their talents. Manufacturers could easily build balls and bats to allow the best athletes to better showcase their skills, but the game would no longer fit the fields as we know them. Would baseball be a better game if every few years new balls and bats were introduced, thus making the balls fly much farther and faster? I don't think so.