MLB Details Slight Changes to Make Baseballs More Uniform, Less Bouncy

An internal memo sent by Major League Baseball to general managers, assistant general managers, and equipment managers that was subsequently obtained by The Athletic outlines plans to make baseballs more uniform in 2021 and beyond. Rawlings — MLB’s official ball supplier, which is also conveniently owned by the league — found that “loosen[ing] the tension of the first wool winding” reduced the weight of the ball by less than one-tenth of an ounce and better centered it in the established coefficient of restitution range.

Um, yeah, what?

That COR range, currently set from .530 to .570, establishes the acceptable “relationship of the incoming speed to the outgoing speed” of the ball. A higher COR means a little more “bounce” off the bat, which means harder hits and more homers. It follows, then, even a slightly deadened ball would result in less offense.

Then again, the ball is also getting slightly smaller. Even something as seemingly minuscule as one-tenth of an ounce could mean less drag on the ball, which could counter the decreased trampoline effect. The Korean Baseball Organization made changes to reduce the COR of their balls but also increased the weight by one gram, resulting in a sharp decrease in home runs.

Per The Athletic, MLB’s memo included a footnote stating that the new balls resulted in one to two feet of decreased distance on fly balls hit over 375 feet. That could be a big deal when you’re talking about a ball clearing the fence in the alley versus finding a home in an outfielder’s glove.

It’s also pointed out that five more unidentified teams will begin using humidors this season, bring the total to 10 teams across MLB. That practice first came into vogue in Denver as a way to counteract the thin air, but the Mariners, Mets, Red Sox, and Diamondbacks also use humidors. These tiny alterations to the makeup and storage of baseballs could end up having a big impact.

Or they might not have any discernible effect whatsoever. The simple fact is that no one will know for certain whether and how the new balls will change the game until they’re put into play. I guess we’ll just have to wait and see.

Ed. note: As a callback those of you perpetually online friends might recall, I imagine this starting with Rob Manfred going to Rawlings with a mandate to “Rebuild my balls.”