Major League Baseball has slightly dampened its baseball due to the increase in the number of home runs in recent years, a source confirmed to the Associated Press on Monday.
MLB anticipates the changes will be subtle, and a note to teams last week quotes an independent lab that found the new balls will fly 1 to 2 feet shorter on balls hit over 375 feet. Five other teams also plan to add humidifiers to their stadiums, which means 10 of MLB’s 30 stadiums are expected to be equipped with moisture-controlled storage spaces.
A person familiar with the story spoke to the Associated Press on Monday, on condition of anonymity, as the note, sent by MLB Executive Vice President Morgan Sword, was sent privately. Athletic first reported the contents of the note.
The composition of official Rawlings baseballs used in MLB games has been examined in recent years. In the regular season of 2019 there was a record of 6,776 home runs, and the home run rate decreased only slightly during the 2020 season shortened by the pandemic: from 6.6% of plate occurrences that led to home runs house in 2019 to 6.5% in the last year.
A four-member committee of scientists, commissioned by MLB, concluded after the 2019 season that baseballs had less resistance on average than in previous seasons, which contributed to increased power. Their report blamed the partial increase in discrepancies in stitch height.
The balls used in MLB are hand-sewn by workers at the Rawlings factory in Costa Rica, leading to inevitable minor deviations in production, which can have considerable repercussions.
The league requires all baseballs to have a refund coefficient (COR), essentially a measure of the ball’s jump, ranging from .530 to .570, but in recent years, the average COR has evolved upward.
In an effort to get the ball right, Rawlings relaxed the tension on the first of the three wires. His research estimates that the adjustment will reduce the COR from .01 to .02 and will also reduce the weight of the ball by 2.8 grams without changing its size. The league does not anticipate that the weight change will affect the pitchers’ speed.
The memo did not address shooting the ball, which remains a more difficult issue to control.
The Colorado Rockies, Arizona Diamondbacks, Seattle Mariners, New York Mets and Boston Red Sox already have humidifiers. The five teams that added humidifiers were not identified in the memo.