Robot umpires will be introduced in Major League Baseball starting with the 2026 season. The league’s 11-member competition committee approved the use of the Automated Ball/Strike System (ABS) on Tuesday.
Under the new system, human plate umpires will continue to call balls and strikes, but teams will have the ability to challenge two calls per game. If a game goes into extra innings, teams will receive additional appeals. Only pitchers, catchers, or batters can initiate a challenge by tapping their helmet or cap. A team keeps its challenge if it is successful. The results of reviews will be displayed as digital graphics on outfield videoboards.
The implementation of robot umpires is expected to reduce ejections related to disputes over balls and strikes. According to MLB data, more than 60% of ejections among players, managers, and coaches last year were due to disagreements about ball and strike calls. This trend has continued through this season.
UmpScorecards reports that big league umpires currently make correct calls on about 94% of pitches.
Cleveland Guardians manager Stephen Vogt commented on the change: “It’s a big change,” Vogt said as Cleveland prepared to open a critical three-game series with Detroit. “We got to see it a little bit at spring training. It’s a new rule and we’re going to have to learn how to use it. We’re going to learn how to adapt to it. You can like it, dislike it, it doesn’t matter. It’s coming. It’s going to change the game. It’s going to change the game forever.”
The ABS uses Hawk-Eye cameras and has been tested in minor leagues since 2019 and in independent leagues such as the Atlantic League during its All-Star Game that year. MLB installed ABS technology for the Arizona Fall League in 2019 and expanded trials across various minor league levels in subsequent years.
In Triple-A baseball at the start of 2023, half of games used robots for calling balls and strikes while others relied on human umpires with an option for teams to appeal decisions using ABS technology. By June 26, 2024, all Triple-A games switched fully to a challenge-based system rather than having robots call every pitch directly.
During spring training this year, MLB used the challenge system at 13 ballparks covering 19 teams for nearly 300 exhibition games; just over half of challenges were successful.
At Triple-A this season so far, teams are averaging slightly more challenges per game compared with last year but have seen their success rate drop below half overall.
A test run at this year’s Major League All-Star Game saw four out of five challenges against plate umpire Dan Iassogna’s calls succeed.
Unlike previous rules at Triple-A where no extra challenges were given in extra innings, MLB’s latest proposal grants one additional challenge per inning if none remain during extras.
MLB has experimented with different strike zone shapes within ABS trials—including three-dimensional versions—but currently uses criteria based on where a pitch crosses an area measured from both front and back edges of home plate relative to batter height.
Commissioner Rob Manfred stated: “Throughout this process we have worked on deploying the system in a way that’s acceptable to players,” he said in an official statement. “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.”
This move marks MLB’s first major rule change since several significant adjustments made for the 2024 season—including introduction of a pitch clock and limits on defensive shifts—which aimed at improving pace-of-play and action during games.
By allowing challenges instead of automating every call outright, MLB preserves some traditional aspects such as pitch framing—a skill catchers use when presenting borderline pitches favorably—though opinions differ regarding its value or legitimacy within professional baseball strategy.
Former manager Bobby Valentine criticized framing: “The idea that people get paid for cheating, for stealing strikes, for moving a pitch that’s not a strike into the zone to fool the official and make it a strike is beyond my comprehension,” he said.
Texas Rangers manager Bruce Bochy recalled older generations’ resistance: Old-school umpires like Bruce Froemming would not have tolerated attempts at deceptive framing tactics by catchers under their watch.
Management officials serving on MLB’s competition committee include Seattle chairman John Stanton; St. Louis CEO Bill DeWitt Jr.; San Francisco chairman Greg Johnson; Colorado CEO Dick Monfort; Toronto CEO Mark Shapiro; Boston chairman Tom Werner; along with player representatives from several clubs based on input from all thirty teams’ rosters.
