MLB Trials Automated Ball and Strike Calls in All-Star Game, Leaving Some Pitchers Less Than Enthusiastic
The Major League Baseball (MLB) introduced its Automated Ball-Strike (ABS) system, also known as the automated strike zone system, during the 2025 MLB All-Star Game in Atlanta. This marks a significant step towards the potential revolution of the game and the reduction of the unpredictability of the strike zone.
The system, which has been in use in the minor leagues and spring training, works by pausing the game when a challenge is made, and a virtual simulation of the pitch is shown on a massive screen beyond right center field. Only the pitcher, catcher, and hitter can challenge a call.
In the All-Star Game, the system was activated when one of these players tapped the top of their cap or helmet twice. The rules for the challenge system are the same as those used in spring training. Each team starts the game with two challenges and keeps their challenge if deemed correct.
While pitchers Tarik Skubal (Detroit Tigers) and Paul Skenes (Pittsburgh Pirates) have expressed unfazed attitudes about the new technology, preferring to let the catcher handle challenges, some players like Los Angeles Dodgers veteran Clayton Kershaw have expressed concerns. Kershaw is particularly concerned about the varying sizes of strike zones across different TV or streaming services.
The strike zone in the automated system is not a fixed box but is personalized based on each batter's height. The system calculates the strike zone as a percentage of the batter's height: the top of the strike zone is set at 53.5% of the batter’s height, and the bottom is set at 27% of the batter’s height. This dynamic approach ensures the strike zone better matches individual batters’ physical stature, increasing fairness and consistency.
The ABS system was installed in 13 spring training ballparks for 19 teams during the latest spring training season. During this period, teams won about 52.2% of their ball/strike challenges, showing a significant use of the system to review calls. The pitch animations and challenge outcomes were also displayed on video boards during these games to enhance transparency and fan engagement.
Before the full regular-season adoption, which is planned for 2026, MLB has not yet implemented the system regularly but plans to do so following approval from the competition committee. The system was notably used in the 2025 MLB All-Star Game as a showcase on a national stage, marking a major step towards acceptance in the majors. During the 2024 regular season, analysis of called pitches showed some discrepancies between human and system calls, with 10.9% of pitches called balls inside the zone and 6.3% called strikes outside the zone, pointing to areas for improvement and the potential benefit of automation.
As the league moves towards full implementation, discussions about the "human element" in baseball, such as errors that can significantly impact games, remain a controversial topic among fans. Some, like Chris Sale, the Atlanta Braves pitcher and reigning NL Cy Young Award winner, prefer to keep the "human element" in the game. However, others, like Clayton Kershaw, hope that the league will ensure different players like Aaron Judge and Jose Altuve have different sized boxes to maintain a level playing field.
References: [1] "MLB All-Star Game 2025: Automated Strike Zone System in Play". ESPN.com. 2025. [2] "MLB's Automated Strike Zone System: What You Need to Know". MLB.com. 2025. [3] "Automated Strike Zone System Debuts at 2025 MLB All-Star Game". Forbes.com. 2025. [4] "Automated Strike Zone System: How It Works". MLB.com. 2025.
The ABS system, debuting in the 2025 MLB All-Star Game, not only showcases the potential of revolutionizing baseball but also provides an opportunity for reducing unpredictability in the strike zone, as it was first used in the minor leagues and spring training. During the All-Star Game, players could challenge calls, and the system's personalized strike zone for each batter, calculated based on their height, aims to ensure fairness and consistency.
As the league prepares for full implementation in the 2026 regular season, debates about preserving the "human element" and the fairness of individual players having different sized strike zones, like Los Angeles Dodgers veteran Clayton Kershaw suggests, continue among fans and players. On the other hand, some players like Tarik Skubal and Paul Skenes have an unfazed attitude towards the new technology, leaving the challenge system to their catchers.
