MLB To Test Check-Swing Rule In Triple-A

"A check-swing challenge system requires an objective cutoff point. The threshold is whether the bat head breaks a 45° angle relative to the handle (essentially aligning with the opposite base line). Major League Baseball's rulebook doesn't have an official check-swing cutoff, instead leaving it at the umpire's discretion as to whether the hitter offered."

"As Longenhagen demonstrates with video, the 45° threshold is further along than what umpires have generally treated as the cutoff. That led hitters to successfully challenge a lot of calls last year. It appears that's a deliberate consideration by the league. MLB's memo notes a slight drop in the Florida State League strikeout rate after the check-swing challenge was implemented."

"The check-swing challenge will only be tested in the Pacific Coast League. In the other half of Triple-A, the International League, MLB will instruct umpires to visually use the 45° degree cutoff but will not give players the right to challenge. That's seemingly to set up some kind of control group vs. the PCL while encouraging umpires to be more forgiving on check-swing calls generally."

Major League Baseball will implement several rule changes across minor league levels in 2026. The most significant is the check-swing challenge system debuting in Triple-A's Pacific Coast League in early May, allowing batters, pitchers, or catchers to challenge umpire check-swing decisions using bat-tracking technology. The system uses a 45-degree angle threshold between bat head and handle as the objective cutoff point, which is more lenient than traditional umpire discretion. MLB tested this rule in Low-A and the Arizona Fall League previously, observing a slight strikeout rate decrease and increased balls in play. The International League will use the same 45-degree visual standard without challenge rights, serving as a control group.

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