MLB tests robot umpires; could debut in 2026 after spring trials
Major League Baseball plans to test robot umpires using a challenge system during spring training across 13 ballparks, involving 19 teams. If successful, this system could make its regular-season debut in 2026.
MLB has been experimenting with the automated ball-strike system (ABS) in the minor leagues since 2019, but they are still refining the strike zone’s structure.
Introducing ABS to the majors would require an agreement with the Major League Baseball Umpires Association, as their collective bargaining agreement ends on December 1, 2024.
In Triple-A ballparks, ABS was used for the second consecutive season this year. However, there is little appetite to stick strictly to the cube-shaped strike zone defined in the rule book. MLB has been tweaking the system during minor league tests to improve its functionality.
Currently, ABS determines strikes by analyzing where the ball crosses the midpoint of the plate—8.5 inches from its front and back edges. This year, MLB adjusted the top of the strike zone to 53.5% of the batter’s height (up from 51%), while the bottom remained fixed at 27%.
For the first three games of each Triple-A series, robot umpires exclusively called balls and strikes. For the last three games, human umpires worked with a challenge system. On June 25, MLB transitioned entirely to a challenge system, where human umpires made most decisions but allowed players to contest calls.
During the second half of the season, teams in the Pacific Coast League had three challenges per game, while teams in the International League were allowed two. Teams retained successful challenges, mirroring the video review rules in the majors.
During game one of the ALCS between the New York Yankees and the Cleveland Guardians, umpires stood for the playing of God Bless America during the seventh-inning stretch at Yankee Stadium.
“I think we will have a spring training ABS test that will provide a meaningful opportunity for all major league players to see what the challenge system will look like,” said MLB Commissioner Rob Manfred. “It won’t be in every single ballpark, but we actually have a plan where every team will get meaningful exposure.”
The decision to test ABS during spring training reflects the league’s intent to gather extensive input from players and teams. According to Manfred, feedback from both groups will play a critical role in shaping ABS’s future.
“There’s two sides to that test,” Manfred added. “It’s what the clubs think about it and also what do the players think about it? And we’re going to have to sort through both of those.”
Before ABS can make its regular-season debut, MLB must finalize an agreement with the Umpires Association, making the upcoming collective bargaining negotiations a pivotal step in the process.
Although ABS has undergone extensive trials in Triple-A games—including systems with robots solely calling strikes and hybrid models with challenges—introducing it to the majors would represent a transformative change in baseball.
The league hopes these spring training trials will allow players and teams to adapt to the technology, ensuring a smoother transition if ABS becomes part of the game.
If successful, the 2026 season could usher in a new level of precision for baseball’s strike zone. However, its implementation will depend on the results of the tests and the outcome of the labor negotiations.
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