NEW YORK -- Major League Baseball will experiment with a technology system to challenge checked swing calls in the Single-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.
The 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.
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.