From Fangraphs, Makes it sound like they have mastered the art of making a baseball. Less seam drag, smoother leather, and a more perfect round to the baseballs.
While one can point to the general trend of batters making greater efforts to elevate the ball — whether to hit it over shifted infielders or not — it’s more accurate to call that an adaptation to the new reality. The scientific evidence again points to the ball itself as being the driving factor. Earlier this week at The Athletic, Dr. Meredith Wills published a follow-up to last year’s breakthrough article, which itself was a follow-up to MLB’s Home Run Committee report. That committee, led by Dr. Alan Nathan, professor emeritus of physics at the University of Illinois, had found that the recent home run spike was caused by a decrease in the ball’s aerodynamic drag, but found no physical difference in the balls that would explain the change.
Conducting her own measurements using digital calipers and disassembled baseballs, Wills concluded that post-2015 balls’ laces, which were an average of nine percent thicker than balls from the 2010-14 period, were producing less bulging at the seams, yielding a more spherically symmetric ball with less aerodynamic drag — thus allowing them to fly further.
For her latest study, Wills examined 39 balls from this season, which she found differed from the 2015-18 balls and even earlier ones. Most notably, she found “demonstrably lower” seams, only 54.6 percent ± 15.0 percent as high as those on balls from previous seasons. By measuring the coefficient of static friction, she also found that the leather on this year’s balls is relatively smoother, concluding, “the static friction for the 2019 balls is 27.6 percent lower, a statistically significant result demonstrating the leather covers are genuinely smoother.” She measured the bulging of the seams and found, “Not only were the 2019 balls virtually round, what bulging they did show was slightly negative, suggesting the seams might be slightly ‘nestled’ into the leather.” The significantly rounder balls, which have thinner laces than last year’s (more in line with 2000-14 samples) produce even less drag than before, and thus even more carry. Wills noted that both the seam and smoothness issues jibe with anecdotal reports from pitchers about difficulties in gripping this year’s balls, as voiced by players such as Sean Doolittle, Jon Lester, and Noah Syndergaard.
As for commissioner Rob Manfred’s recent suggestion that a better-centered pill (the core of the ball) is a factor in creating less drag, Wills was largely dismissive, writing, “[T]his is the most difficult result to produce without significant manufacturing changes, since existing techniques make it hard to keep the pill from being centered to begin with… Therefore, it seems unlikely that pill-centering would explain a sudden change in drag; at the very least, we would be remiss not to also examine other possible sources.”
Edited by SomeGuy, 28 June 2019 - 12:53 PM.