Forward-looking: Major League Baseball is testing a computerized system for calling balls and strikes during spring training exhibition games. This Automated Ball-Strike System (ABS), which has been in development for four years in the minor leagues, could aid MLB home plate umpires as early as 2026. The ABS uses a network of cameras installed in stadiums to track each pitch and determine whether it crosses home plate within the strike zone. The current iteration uses Hawk-Eye pose-tracking cameras, with most spring training ballparks equipped with eight cameras, though the Diamondbacks/Rockies stadium boasts 12. Before a team's first test game, each batter is measured with shoes off to calibrate their individual strike zone, a process that takes less than a minute.The latest version of ABS introduces a challenge system, adding a new dimension to the game. During spring training, human umpires will continue to call every pitch, but each team will have two challenges per game. Only batters, pitchers, or catchers can initiate a challenge within two seconds of a call, signaling with a tap of their helmet or cap.When a challenge is made, a graphic of the pitch and strike zone will be displayed on the scoreboard and broadcast feed. The umpire then announces the updated count. MLB estimates this process takes an average of 17 seconds.MLB has installed the ABS system in 13 spring training ballparks, home to 19 teams across Florida and Arizona. Approximately 60 percent of spring training games are scheduled for ABS testing, though the number of games with the system varies significantly between teams.The ABS strike zone has undergone several modifications since its inception. Initially set at 19 inches wide in 2022, it was narrowed to 17 inches to match home plate width. The top of the strike zone was raised from 51 percent to 53.5 percent of a batter's height in 2024 following pitchers' complaints. // Related StoriesUnlike the human-called strike zone, which is typically oval-shaped, the ABS zone is rectangular. The system makes ball/strike decisions at the midpoint of the plate, contrasting with the rulebook definition of the strike zone as a cube.MLB began experimenting with ball/strike technology in the independent Atlantic League in 2019. The system was gradually introduced to minor league levels, reaching all Triple-A stadiums by 2023.In the 2023 Triple-A season, teams had a 51 percent overall success rate with challenges. Challenges were more frequent later in games and on critical counts, with 8.2 percent of full-count pitches being challenged.The introduction of ABS has led to slight increases in both strikeout and walk rates. In full ABS games, strikeout rates increased by 0.5 percent, while walk rates rose by one percent. In challenge games, walk rates increased by 0.8 percent.To prevent fans from potentially influencing challenge decisions, MLB is exploring various broadcast alternatives. These include showing the strike zone box without the ball, displaying the ball without the box, or only showing the corners of the box.MLB has also implemented a system for players to provide feedback on the ABS. An application called ProTABS, available on dugout iPads, allows players to review pitches against their individual strike zone and comment on both single pitches and the overall system.