Major League Baseball has announced that the Automated Ball-Strike (ABS) Challenge System will be implemented full time starting in the 2026 season. The decision was made by the Joint Competition Committee following several years of trials in Minor League Baseball, as well as use during MLB Spring Training and the All-Star Game.
MLB Commissioner Rob Manfred stated, “The previous rule changes that have been adopted by the Joint Competition Committee have had staying power and created momentum for the game. We used the same process with ABS that started with listening to fans, conducting extensive testing at the Minor League level, and trying at every step to make the game better. Throughout this process we have worked on deploying the system in a way that’s acceptable to players. The strong preference from players for the Challenge format over using the technology to call every pitch was a key factor in determining the system we are announcing today.”
The ABS Challenge System is seen as a compromise between using automated systems for every pitch and maintaining traditional human umpiring. It allows teams to challenge ball or strike calls they believe were incorrect. When challenged, Hawk-Eye technology determines whether a pitch was within or outside of the strike zone. The results are shown quickly on stadium videoboards and television broadcasts.
Mike Katz, president of marketing, strategy and products at T-Mobile, commented on his company’s involvement: “We’ve accomplished a lot through our longstanding partnership with MLB, and the rollout of ABS — powered by T-Mobile 5G — is one of our most exciting milestones yet. It’s a powerful example of how we’re using our technology to help MLB innovate, while preserving the character of the game we love. And it’s only possible with the scale and reliability of America’s Best Network.”
Each team will begin games with two challenges. If a game goes into extra innings and a team has no remaining challenges, it will receive one additional challenge per inning as needed.
Challenges can only be issued by batters, pitchers or catchers immediately after an umpire’s call—managers cannot initiate them. Players signal their intent by tapping their cap or helmet.
Data from Spring Training 2025 showed an average of just over four challenges per game, each taking roughly 14 seconds to resolve. Teams retain successful challenges; if an umpire’s call stands after review, they lose that challenge.
Surveys conducted during testing revealed positive feedback from both fans and players regarding this system. According to Major League Baseball surveys from Spring Training, about 72% of fans reported that ABS had improved their experience watching games.
Testing began in independent leagues in 2019 before expanding through various levels of Minor League Baseball over subsequent seasons. Research indicated that both fans and baseball personnel preferred retaining some human element rather than moving entirely to automated calls for every pitch.
The new strike zone determined by ABS is based on precise player measurements without cleats; its width matches home plate at 17 inches but uses specific percentages relative to player height for top (53.5%) and bottom (27%) boundaries.
During trials at Triple-A level prior to implementation in MLB games, two-challenge formats were found preferable because they limited total interruptions while still allowing key plays to be reviewed when necessary.
The ABS Challenge System will be used throughout all regular season games across every ballpark as well as during postseason play starting in 2026.
