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.

The Automated Ball-Strike System

After the initial attempts at a fully automated umpiring system, MLB decided to test an alternative system in the minor leagues, the "ABS Challenge System", ABS standing for "Automated Ball-Strike". Under this system, the home plate umpire still makes the initial ball and strike decisions, but each team is allotted two challenges, which can only be initiated by the pitcher, the catcher or the batter (but not by a manager or coach), after which the 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 15 seconds on average, and is only used three or four times per game. A team retains its challenge if it is successful, but loses it otherwise, and can receive additional ones if the game goes into extra innings.

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. It was also used at the 2025 All-Star Game, in another sign that it would be part of regular season major league games in short order. Indeed, on September 23rd, MLB made the official announcement that the system would be introduced during games in the 2026 season.

The first player to initiate a challenge was José Caballero of the New York Yankees, in the 4th inning of the opening game of the season against the San Francisco Giants on March 25th. He challenged a called strike by home plate umpire Bill Miller on a pitch by Logan Webb, but the video review confirmed that the call had been correct. The challenge had no impact on the game, as the Yankees already led, 5-0, at the time, and ended up 7-0 winners. The first successful challenge came the following day, when on a full count, New York Mets catcher Francisco Álvarez successfully challenged a ball call by home plate umpire Adrian Johnson; the successful challenge resulted in Oneil Cruz of the Pittsburgh Pirates being called out on strikes.

There was bound to at some point be a game that ended on a challenge, and fans did not have to wait long for that to happen, as on April 1st, a game between the Texas Rangers and the Baltimore Orioles ended in this fashion: with a 1-2 count on the Rangers' Evan Carter, the next pitch from Albert Suárez was called a ball by home plate umpire Manny Gonzalez but C Samuel Basallo appealed, and when the call was reversed, Carter had struck out and the game ended with an 8-3 win for the Orioles. Granted, it would have been more exciting had Carter represented the tying or go-ahead run, but nonetheless it was a first.

Further Reading

• Anthony Castrovince: "MLB to test automated ball-strike challenge system during spring games", mlb.com, February 18, 2025. [1]
• Anthony Castrovince: "ABS Challenge System coming to MLB full time in '26", mlb.com, September 23, 2025. [2]
• Anthony Castrovince: "Everything you need to know about the new ABS Challenge System", mlb.com, February 12, 2026. [3]
• Sonja Chen: "Dodgers and Cubs get first look at automated ball-strike challenges", mlb.com, February 20, 2025. [4]
• Mark Feinsand: "Commissioner: Automated ball-strike system a possibility, but unlikely to take place by '25", mlb.com, May 23, 2024. [5]
• Jimmy Golen (Associated Press): "Robo umps reach Triple-A, but MLB rollout still uncertain", Yahoo! News, May 9, 2023. [6]
• Bryan Hoch: "A historic first strike challenge was ... upheld!", mlb.com, May 26, 2026. [7]
• Mike Petriello: "There's loads of ABS data from last season. What does it all mean? Who's the best and worst at it? How often does it happen? And more", mlb.com, February 26, 2026. [8]
• Manny Randhawa: "Automatic strike zone coming to AAA in '22", mlb.com, January 21, 2022. [9]
• Jake Rill: "We can say with certainty, no MLB game has ever ended like this before", mlb.com, April 1, 2026. [10]