The golf ball rollback could have this unintended consequence. A top golf physics expert explains why

What if the proposed ball rollback doesn’t actually roll back performance among elite golfers? Sasho MacKenzie, among golf’s very short list of leading biomechanists, posed the question Monday to a panel that featured representatives from the USGA and R&A.

“I think we're getting very, very confident in what we think will happen because we have all this information, but really, it's the unseen information that's really going to change things,” Mackenzie said during a virtual summit on the golf ball rollback hosted by the Golf Journalists Association of Canada and RBC.

“If we roll the ball back on the tour level, there's going to be an explosion in clubhead speed that they're not predicting.”

Mackenzie, a professor in the department of human kinetics at Canada’s St. Francis Xavier University, has studied the biomechanics of the golf swing and the interaction between equipment and elite performance for much of the last 20 years. He roots his suggestion in golf’s ruling bodies’ proposed change to the ball testing method.

Announced this spring, if adopted, the new rule would change the speed at which balls are tested for conformance, increasing it from 120 mph to 127 mph. That effect would require balls to fly 15-20 yards shorter than they do currently to be conforming to the test. Mackenzie believes that kind of rollback actually might have the unintended consequence of further emphasizing a pursuit for distance, or, more precisely, clubhead speed. And in Mackenzie’s view of the future of a rolled back ball, that potential for swing speed is monumentally higher than it is now.

"We're talking about the best of the best, a very, very small percentage of athletes," Mackenzie said, "but if you start playing with a ball that gets slower and slower in terms of the distance it's going off the tee, players will start swinging faster and faster, and all of a sudden players that cannot swing the club at 130 and 140 miles an hour will not be in the game. I think 160 is the limit that we're kind of working around with [in terms of] human potential. There is no reason to think that the top .005 percent of the golfers in the world won't figure out how to swing a golf club at 140 miles an hour in the next 10 years. I don't see it going any other way.”

A swing speed explosion?

If Mackenzie’s prediction is true, that would increase the average swing speed on the PGA Tour by more than 25 mph. If every mile per hour of swing speed would lead to approximately 2.5 yards of distance, that would increase current driving distance by more than 60 yards. Now, if there were a ball rollback, some of that increase would be clawed back by perhaps 15-20 yards. But Mackenzie also wondered what the effects of a new ball actually might be. The modern game hasn't really experienced switching to equipment that performed significantly worse.

Specifically, we don’t entirely know how these new “slower” golf balls will perform or how elite golfers would view the statistical advantage of driving distance. For example, these new balls might yield less than two yards for every mile per hour as you get into the higher speeds. Conversely, given course designs, there may be less statistical advantage for being 350 yards off the tee vs. 315.

The point is whether the push for distance under current conditions is somewhat self-limiting. Any degree of miss is magnified the farther you hit it. Think of tee shots fitting into a cone where the point starts at the clubface. The degree of the mis-hit direction represents how far off line the ball will be. At 100 yards, that might be a five-yard miss, but that same miss at 300 yards becomes more like 20 yards. So the desire for more distance requires more elite face control at 350 yards than it does at 310. And if 310 gets you a wedge into the green, are you necessarily going to be more accurate with a half-wedge? It's not clear.

And to be fair, Mackenzie isn't suggesting that all the current players swinging at average tour speeds will somehow train their way up to swing speeds in the 140s. Rather, the thought is that in some not-too-distant future, the prototypical tour player will be developing these kinds of speeds as almost a prerequisite to be competitive in elite golf. The rolling back of the ball might not lessen the advantage or the value of swinging faster. Rather, Mackenzie said, it very well might increase it to the point of eliminating an entire class of player from the game.

"That means that the David Toms, the Zach Johnsons, you'll never hear from them again. That's the reality," Mackenzie said.

Another unknown is the physical requirements of drastically increasing swing speed at the elite level. At least currently, this kind of skill set development is not without its own consequences. Even Bryson DeChambeau backed off his extreme pursuit of speed after injuries started cropping up. Then again, we also don’t even know whether the proposed rollback will go through (the deadline for comments is Aug. 14).

John Spitzer, the USGA’s manager of equipment rules, also spoke during the GJAC summit, and he suggested that any dramatic changes in average clubhead speed might not happen so rapidly, or at all. He pointed to long drive competitors as an example of the potential for clubhead speed. (Two-time World Long Drive champion Kyle Berkshire has swing speeds of 145 mph and higher, and current champ Martin Borgmeier has reached 156 mph.) But he also stressed that because that sport only requires players to hit one ball of every six in a grid much wider than a typical elite tournament fairway, that PGA Tour players might not increase their swing speed that quickly.

Still, Spitzer noted that elite-level distance isn't exclusive to improvements in club and ball technology. Using comprehensive data from the PGA Tour that includes playing statistics, players' height, weight and age, and specific course setups, he said, "We can separate all those out and what you can see is that it's actually the players' athleticism which has really driven increases in distance over the last several years."

'They're going to start hitting the slower ball just as far'

Mackenzie didn’t necessarily suggest that elite-level distance would be growing exponentially or at all, but he also believes that a certain level of distance will be required to be an elite competitor, and the motivation of a less-responsive golf ball will push a greater percentage of tour players to swing fast enough so the new ball for them doesn’t go shorter.

His prediction is that swinging at less than 130 mph might put an elite player at too much of a disadvantage at some point precisely because of the shorter ball. A faster swinger will be able to maintain current distances, and more players will be able to stay on tour because they swing that fast, while players who swing slower simply won’t be able to compete.

“The folks that can train, they're going to get faster and they're going to start hitting the slower ball just as far as they are now,” Mackenzie said. He said he wasn’t surprised that swing speeds on the PGA Tour are up almost two mph in the last five years to 115.2 mph.

“I'm surprised it hasn't gotten faster quicker,” he said.

It’s not clear how much further the rule would reach, but already it’s been suggested that NCAA Division I golfers would want to play with such a ball, and the AJGA would want its elite competitions to use such a ball, too.

Spitzer stressed that the proposed change was developed specifically to not impact average golfers. “The short answer is: That's what the vast majority of the golfing public wants,” he said. “Now, I might believe personally that five to 10 yards is not substantial for a recreational golfer who has a range of their distance off the driver that might be plus- or minus-30 yards, so that they may not even notice. Plus, they can move up a little on the tee. But it turns out that most recreational golfers think anything more than zero is a substantial reduction. And you have to keep in mind that older players and women, one or two yards can be a big difference, especially with forced carries. There’s a lot of things that go on with it.”

Also part of the discussion was Dr. Mark Grattan, the director of equipment standards for the R&A. He emphasized that not doing anything with regard to distance at this point was possibly ignoring the opportunity to give courses or tournaments the option of adopting a shorter ball. That’s the reason the ruling bodies have proposed the rule change as a “model local rule” rather than a universal change that applies to all golfers.

“It's a case of looking at the data we’ve seen over the last number of years, and the risk is, is if we do nothing, what happens?” he said. “We've got to look at the future of the game, making sure that we're protecting the balance over time, trying to reduce the pressure to increase the distance of golf courses. I think the MLR gives people the choice as to whether they use it or not.”

The presentation can be viewed at the GJAC website.