Major League Baseball will experiment with a technology system to challenge checked swing calls in the Class A Florida State League starting Tuesday.
Using a Hawk-Eye system, a checked swing call can be challenged by either the team at bat or on defense.
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WATCH HEREThe decision will be made based on whether the bat head is ahead of the knob by more than 45 degrees — matching the first-base line for a right-handed hitter and the third-base line for a left-handed hitter. Short of 45 degrees will be called a no swing.
A team will be allowed to make a challenge until it has one unsuccessful challenge. A video of the Hawk-Eye determination of the maximum bat angle will be shown on the ballpark video board.
The team on defense can still ask the plate umpire to check a non-swing call with the first-base umpire for right-handed batters and third-base ump for left-handed batters without using a challenge.
MLB experimented with the system in some Arizona Fall League games last year at Salt River Fields.
There is no definition of a checked swing in the Official Baseball Rules, through it references checked-swing appeals.
MLB
The start of the test was first reported by The Wall Street Journal.
MLB experimented with an Automated Ball-Strike System using the Hawk-Eye system during 288 spring training games this year, and teams won 52.2% of their ball/strike challenges. MLB commissioner Rob Manfred said regular-season use in 2026 is possible but not definite.
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