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Automated Ball-Strike System
The Automated Ball-Strike (ABS) System is a system to automate the interpretation of whether pitches are in the strike zone in baseball games. It has been used by the KBO League in South Korea, and by Minor League Baseball (MiLB) and Major League Baseball (MLB) in the United States. In MLB and MiLB, it is used to enable player challenges of umpire calls of balls and strikes, while in the KBO League and previously in MiLB, it calls pitches automatically.
The independent Atlantic League first used ABS, nicknamed "robot umpires", during its 2019 all-star game. Umpires used earpieces to receive ball-strike calls using TrackMan technology. Umpires could make a call based on the automated message, or could make their own call if the automated system malfunctioned or registered a call with which the umpire disagreed.
The Arizona Fall League began using ABS during its 2021 season. The technology drew complaints from players and fans for its treatment of breaking balls as strikes even when they break and drop out of the strike zone. Human umpires were obligated to make a call based on ABS, and players could be ejected if they contested a call, as with all ball-strike calls.
The Florida State League, a low-A league in Florida, used ABS in its 2021 season. The Major League Baseball Umpires Association (MLBUA) agreed to cooperate and assist if MLB commissioner Rob Manfred decided to use ABS at the major league level, as part of the MLBUA's contract with MLB in 2020.
Five Triple-A baseball stadiums used ABS in 2022, and the system expanded to all stadiums at that level in 2023. In 2023, Triple-A baseball used ABS with and without a challenge system; without a challenge system, human umpires relayed automated calls, and with the system, an automated call would be used only when a team requested a challenge. In 2024, Triple-A teams that played six-game series first used ABS without a challenge system for the first three games, and with challenges for the latter three; starting on June 25, MLB announced that only the challenge system would be used. In 2024, 51% of challenges in Triple-A games were successful.
The KBO League, in South Korea, started to use ABS in its 2024 season. Unlike in MLB, KBO uses ABS to call balls and strikes automatically.
ABS was in place for Spring Training before the 2025 MLB season. Thirteen Spring Training ballparks, used as home fields by 19 clubs, are equipped with ABS technology. MLB implemented ABS as a challenge system; human umpires make initial calls, which pitchers, catchers, and batters may challenge.
MLB used ABS for the 2025 All-Star Game, with a similar configuration to spring training: each team had two challenges, which could be requested by the pitcher, catcher, or hitter immediately after a call. Cal Raleigh, the first player to request an ABS challenge in an MLB All-Star Game, successfully challenged the umpire's ball call of a pitch he caught from Tarik Skubal, resulting in Manny Machado being called out on strikes. Jacob Wilson was the first batter to challenge a call, successfully getting a pitch from MacKenzie Gore changed from a strike to a ball.
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Automated Ball-Strike System
The Automated Ball-Strike (ABS) System is a system to automate the interpretation of whether pitches are in the strike zone in baseball games. It has been used by the KBO League in South Korea, and by Minor League Baseball (MiLB) and Major League Baseball (MLB) in the United States. In MLB and MiLB, it is used to enable player challenges of umpire calls of balls and strikes, while in the KBO League and previously in MiLB, it calls pitches automatically.
The independent Atlantic League first used ABS, nicknamed "robot umpires", during its 2019 all-star game. Umpires used earpieces to receive ball-strike calls using TrackMan technology. Umpires could make a call based on the automated message, or could make their own call if the automated system malfunctioned or registered a call with which the umpire disagreed.
The Arizona Fall League began using ABS during its 2021 season. The technology drew complaints from players and fans for its treatment of breaking balls as strikes even when they break and drop out of the strike zone. Human umpires were obligated to make a call based on ABS, and players could be ejected if they contested a call, as with all ball-strike calls.
The Florida State League, a low-A league in Florida, used ABS in its 2021 season. The Major League Baseball Umpires Association (MLBUA) agreed to cooperate and assist if MLB commissioner Rob Manfred decided to use ABS at the major league level, as part of the MLBUA's contract with MLB in 2020.
Five Triple-A baseball stadiums used ABS in 2022, and the system expanded to all stadiums at that level in 2023. In 2023, Triple-A baseball used ABS with and without a challenge system; without a challenge system, human umpires relayed automated calls, and with the system, an automated call would be used only when a team requested a challenge. In 2024, Triple-A teams that played six-game series first used ABS without a challenge system for the first three games, and with challenges for the latter three; starting on June 25, MLB announced that only the challenge system would be used. In 2024, 51% of challenges in Triple-A games were successful.
The KBO League, in South Korea, started to use ABS in its 2024 season. Unlike in MLB, KBO uses ABS to call balls and strikes automatically.
ABS was in place for Spring Training before the 2025 MLB season. Thirteen Spring Training ballparks, used as home fields by 19 clubs, are equipped with ABS technology. MLB implemented ABS as a challenge system; human umpires make initial calls, which pitchers, catchers, and batters may challenge.
MLB used ABS for the 2025 All-Star Game, with a similar configuration to spring training: each team had two challenges, which could be requested by the pitcher, catcher, or hitter immediately after a call. Cal Raleigh, the first player to request an ABS challenge in an MLB All-Star Game, successfully challenged the umpire's ball call of a pitch he caught from Tarik Skubal, resulting in Manny Machado being called out on strikes. Jacob Wilson was the first batter to challenge a call, successfully getting a pitch from MacKenzie Gore changed from a strike to a ball.