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MLB plans to deaden baseballs, per reports

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2016-20 saw the five highest home run rates in MLB history

An official Rawlings Major League Baseball for the 2020 Major League Baseball season. Photo by Tim Clayton/Corbis via Getty Images

After a surge in home runs in recent years, Major League Baseball is reportedly deadening the baseball, per reports by Ken Rosenthal and Eno Sarris at The Athletic and by Jake Seiner at the Associated Press.

From Seiner:

In an effort to better center the ball, Rawlings has loosened the tension on the first of three wool windings within the ball. Its research estimates the adjustment will bring the COR down .01 to .02 and will also lessen the ball’s weight by 2.8 grams without changing its size. The league does not anticipate the change in weight will affect pitcher velocities.

From Rosenthal and Sarris:

The MLB memo includes a footnote that says an independent lab found that fly balls that went over 375 feet lost one to two feet of batted ball distance with the new ball. That also sounds like no big deal, but every 3.3 feet of distance increases the likelihood of a home run by ten percent. An analyst familiar with the physics and math of this situation said the relationship was linear enough to estimate that this change will reduce home run rates by around five percent.

“It’ll be like adding five feet of outfield walls to every wall in the big leagues,” the analyst said. But it’s hard to know the specifics without knowing what the drag difference will be. The memo mentions nothing about the drag, which has been a major factor in differences in how the ball has performed in the last few years. Drag is more difficult to control than bounciness, one source said. Others felt the drag difference would be negligible.

The last five seasons have featured the five highest home run rates in MLB history, including a home run in 3.46 percent of all plate appearances in 2020. The only higher rate came in 2019, with a home run in 3.63 percent of all PA.

MLB trying to find more consistency in baseballs comes after years of differences in drag rates, and changes to the seams and leather of the ball itself, researched extensively by Dr. Meredith Wills on numerous occasions, and from Robert Arthur at Baseball Prospectus.

David Price chimed in on the subject on Tuesday morning:

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