During the 2023 season, when Amed Rosario split time between the Guardians and Dodgers, he had an average bat speed of 71.3 mph.

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Three years later, albeit with five months left in the Yankees’ regular season, that number has ticked up to 74 mph, and the results have followed — higher bat speed turning into higher exit velocity turning into more power, which, combined with improved launch angle, can turn into more home runs.

The difference? Rosario spending the past three offseasons working at Driveline, the data-driven baseball factory, to improve his bat speed and launch angle.

“It’s usually a little bit harder for a 30-year-old, long-time established big leaguer to gain [bat speed],” Tanner Stokey, the director of hitting at Driveline, said in a phone interview. “But it is the trend you typically see on somebody who’s typically worked with us year over year over year.