Major League Baseball (MLB) is set to test robot umpires in a challenge system during its spring training at 13 ballparks hosting 19 teams. The technology, known as the Automated Ball-Strike (ABS) system, has been experimented with in the minor leagues since 2019. The system uses camera and Doppler radar sensors to track the trajectory and speed of the ball and determine whether it is a strike or ball.
Under the current system, ABS calls strikes solely based on where the ball crosses the midpoint of the plate. However, MLB has also experimented with modifications to the strike zone, including raising the top of the strike zone to 53.5% of batter height and keeping the bottom of the zone at 27%.
The spring training test will involve a human umpire making nearly all calls, with ABS being used to challenge certain decisions. Each team will have the opportunity to use three or two challenges, depending on the league, and retaining their challenge if successful, similar to the video review system used in big league games.
Commissioner Rob Manfred expressed interest in implementing the system in 2026, but will need to reach an agreement with the Major League Baseball Umpires Association before doing so. The experiment will be evaluated based on feedback from players and coaches, and will provide every team with meaningful exposure to the system.