MLB report blames seam height, not juiced balls, for 2019 home run surge
SAN DIEGO -- This morning Major League Baseball released a report from a committee of scientists tasked with studying baseballs and the home run surge from 2019. Their verdict: that manufacturing variation leading to inconsistent seam height -- not any intentional act taken to “juice” baseballs -- is the reason for last year’s power explosion.
There were 6,776 home runs hit during the regular season, which shattered the previous record, set in 2017, by nearly 11 percent. Numerous players around the league suspected or assumed that the league, which owns the ball manufacturer, Rawlings, had intentionally juiced the baseball to promote offense. The committee concluded in the report that “no evidence was found that changes in baseball performance were due to anything intentional on the part of Rawlings or MLB and were likely due to manufacturing variability.”
That conclusion would appear to only be partially accurate.
Dr. Meredith Wills, an astrophysicist who has been conducting her own research on baseballs and the home run explosion, published her own work on all of this in The Athletic last June. Wills concluded that, based on her examination of baseball seams and seam height, a key part of the manufacturing process -- the drying of damp, finished baseballs after assembly is complete -- likely did change.
Specifically, she concluded that seam height and decreased bulging of baseballs which led to less aerodynamic drag and farther ball flight was likely the result of Rawlings using heaters to dry balls, as opposed to the traditional air-drying, allowing them to produce more balls in a shorter period of time. Wills told NBC Sports this morning that she suspects Rawlings did this because many more balls were needed due to Major League Baseball mandating that Triple-A adopt the major league ball for the 2019 season.
As such, the key word in this morning’s report is “intentional.” Wills:
There is also the matter of the decrease in ball flight and home runs observed -- and confirmed by today’s report -- in the 2019 postseason.
MLB’s expert panel basically punts on any explanations for the variation, noting small sample size and no other apparent explanation. As such, the matter for the immediate change in the home run rate and fly ball distance the moment we moved from September to October baseball is not clear. Wills is continuing her research on 2019 postseason game balls -- a matter about which there has already been no small amount of controversy of late -- and expects to publish her results soon.
There will be a press conference regarding the study here at the Winter Meetings at 1PM Eastern time today. NBC Sports will be at that press conference. NBC Sports has a good number of followup questions.