For the first time since 2021, baseballs have been flying out in Japanese parks at somewhat normal rates, causing Katsuhiko Nakamura, Nippon Professional Baseball’s secretary general, to issue the standard response on April 6 that NPB has not been messing with its balls.
“There has been absolutely no intentional change in specifications,” he said.
Back in the 1990s, before I worked in the mainstream media, Nakamura was in charge of ball certification and testing, a much harder job than it is now with, ostensibly, just one ball used by all 12 teams. Unfortunately, Sankei Shimbun on April 24, reported that a source attending a Nov. 10 executive committee meeting said Nakamura revealed a proposal by ball manufacturer Mizuno to increase the coefficient of restitution by winding the yarn within balls tighter, making them harder with a higher coefficient of restitution, so they retain more energy from the collision with the bat and thus fly farther.
In March, the article reported that teams were told the livelier balls tested by Mizuno last September would be used at the beginning of this season.
After the 2024 season, when the frequency of fly balls that went for home runs was nearly 25 percent of the average from the previous three seasons, people within NPB were telling me and others on the condition of anonymity that the cause was poor quality control after Mizuno shifted its manufacture of balls from the China to Taiwan.
It is unclear when NPB realized it had a 2024 home run disaster on its hands with barely half as many home runs as the same months from 2021 to 2023, but the balls in the second half proved somewhat livelier. Dr. Meredith Wills, who knows as much about the makings of baseballs and their manufacture as anyone, told me that winter that the logistical tail needed to produce a season’s worth of balls meant that NPB and Mizuno had to have begun to fix the problem months before the start of the 2024 season – when NPB also admitted no change had been made to the balls.
Every time there is a discussion of whether the balls are either more or less lively, NPB asserts that no changes have been made to the COR. MLB did the same in 2018, when balls were leaving parks much more often. That was when Wills discovered that the yarn used to stitch MLB’s balls used that year was thicker and stronger, allowing them to remain more aerodynamically efficient after the collision with the bat so balls hit with the same force would fly further.
Of course, even that pronouncement is suspect, since at least one source reported that the balls were in fact changed.
This gets us no closer to the mystery of how the balls have gradually gotten deader year by year, when nothing was supposed to have changed, and even more important, why.
After purchasing its ball manufacturer Rawlings, MLB commissioner Rob Manfred told a press conference at the 2018 winter meetings that the reason was to ensure quality control. When quizzed about the incredible variance that had been observed, Manfred snapped that uniformity could not be expected in baseballs, by virtue of their being hand-sewn.
One of the adjustments Japanese pitchers face when confronted with MLB balls in addition to their slicker covers, higher seems and larger size, is their lack of conformity. The level of uniformity among NPB balls is one of their features. That’s what makes the steady decrease in home runs even more suspicious.
