Robot Umpires: ABS Overturn Rates and Impact on MLB Season One
“It’s like a new muscle for players to learn,” Yankees manager Aaron Boone said, capturing the adjustment period as the Automated Ball-Strike System completed its debut season. In the first year of the ABS challenge system, robot umpires overturned 54% of challenged calls, with catchers proving significantly more successful at challenging ball-and-strike calls than batters or pitchers.
Ten Thousand Challenges Across the Major Leagues
Major League Baseball saw 10,557 total challenges during the season, averaging 4.35 per game. Of those appeals, 5,686 led to overturned decisions. Catchers led all positions in success, winning 59% of their challenges. Batters posted a 49% success rate, while pitchers challenged infrequently and succeeded 40% of the time.
Players and managers quickly learned that knowing when to challenge was just as important as the technology itself. ABS heavily impacted the game by forcing hitters to be more selective and disciplined while compelling pitchers to attack the strike zone more aggressively, according to Houston Manager Joe Espada.
Cincinnati Reds Lead in Net Runs from Challenges
The Cincinnati Reds led all teams with a net gain of 16.8 runs from challenges.
Individual players also shaped these margins. Among catchers, Milwaukee’s William Contreras led with 5.2 projected runs prevented, closely followed by Cleveland’s Patrick Bailey at 5.1 runs.
Challenge Volume Peaks in Ninth Inning
Because teams lose their right to challenge after two incorrect appeals, usage patterns shifted by inning. Teams used ABS less frequently in the early innings, averaging 1,005 challenges with a 61% success rate across innings one through three. Conversely, the ninth inning saw the highest volume with 1,366 challenges, though success dropped to 40% as clubs spent remaining appeals before games ended.
Overall challenge frequency climbed as the season progressed. Challenges rose from an average of 3.76 per game in March to 4.60 in August and 4.61 in September, driven largely by an increase in catcher appeals.
Andy Fletcher Records Highest Umpire Overturn Rate
Individual home plate umpires experienced varying reversal frequencies under the review system. Andy Fletcher recorded the highest overturn rate among umpires with more than 100 challenges, getting reversed on 66.1% of 121 calls, according to taptochallenge.com.