Major League Baseball used at least two types of balls again this year, and evidence points to a third
An Insider investigation based on research by Meredith Wills found evidence that during this season, MLB circulated three distinct sets of game balls.
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While Wills' research found "dead" balls at parks around the country, the "Goldilocks" balls — with a more batter-friendly weight profile — only turned up at Yankees games and marquee events like the postseason or games using balls with commemorative stamps.