The New York Yankees’ historic nine-home run day against the Milwaukee Brewers on Saturday was overshadowed by a question that has sparked debate across Major League Baseball: what bats are being used? The answer, according to Aaron Leanhardt, the team’s lead analyst and inventor of the unique, torpedo-shaped lumber.
Leanhardt’s design is the result of two years of research and experimentation with a former Massachusetts Institute of Technology physicist turned coach. The uniquely shaped bat is custom-made to player preferences and is designed to concentrate weight in areas where players most often make contact with the baseball.
MLB Rule 3.02 states that bats shall be a smooth, round stick not more than 2.61 inches in diameter at the thickest part and not more than 42 inches in length. However, Leanhardt’s design falls under “experimental” bats, which are only allowed if MLB approves their design and manufacturing methods.
Leanhardt says he did not invent the technology alone but credits conversations with coaches, players, and bat makers for its development. Yankees officials praise Leanhardt as a key contributor to the innovation, while some question whether his design actually breaks any rules.
The debate surrounding Leanhardt’s bats raises questions about innovation in sports and the willingness of athletes to push boundaries. With five Yankees players using the new bats in games this season, it remains to be seen how long this trend will last in the sport.
Source: https://www.nytimes.com/athletic/6241862/2025/03/30/yankees-bats-aaron-leanhardt-marlins