Robot umpire

A robot umpire, also sometimes called Robo Ump in tribute of the classic 1987 science fiction film RoboCop, or more formally an "automated ball-strike system", is a mechanical system that calls balls and strikes instead of the home plate umpire. It has been tested out in some independent leagues and in the Arizona Fall League, and in 2021 was introduced to some Low A leagues in Minor League Baseball, with a view to eventually introduce it at all levels of professional baseball if it proves to work fine. In 2022, its use was moved up all the way to AAA as it seemed inevitable that it would be adopted by the major leagues within a short time frame. In May of 2024, Commissioner Rob Manfred stated that such a system was unlikely to be implemented by the 2025 season, as there were still some issued to work out at the minor league level.

Under this system, there is still a home plate umpire, but his role is limited to calling any play at the plate, and making some specific calls, such as foul tips, checked swings, a batter deliberately being hit by the baseball, or a ball crossing the strike zone on a bounce. For all other calls, he simply records the decision made by the system.

After the initial attempts at a fully automated umpiring system, MLB decided to test an alternative system in the minor leagues, under which the home plate umpire still made initial ball and strike decisions, but each team was allowed a number of challenges, which can only be initiated by the pitcher, the catcher or the batter (but not by a manager), during which the Automated Ball-Strike System comes into play. The result of the challenge is then shown on the scoreboard, similar to what is done in tennis tournaments where the "Hawk-Eye" technology is used. The whole challenge process takes less than 30 seconds, and is only used three or four times per game. After the challenge system was used with success in AAA in both 2023 and 2024, MLB introduced it for spring training games in 2025 as a test to determine whether it was something that could come to major league games in future years.

Further Reading

• Anthony Castrovince: "MLB to test automated ball-strike challenge system during spring games", mlb.com, February 18, 2025. [1]
• Sonja Chen: "Dodgers and Cubs get first look at automated ball-strike challenges", mlb.com, February 20, 2025. [2]
• Mark Feinsand: "Commissioner: Automated ball-strike system a possibility, but unlikely to take place by '25", mlb.com, May 23, 2024. [3]
• Jimmy Golen (Associated Press): "Robo umps reach Triple-A, but MLB rollout still uncertain", Yahoo! News, May 9, 2023. [4]
• Manny Randhawa: "Automatic strike zone coming to AAA in '22", mlb.com, January 21, 2022. [5]