Major League Baseball's Automated Ball-Strike System (ABS), introduced for the first time this season, is visibly reshaping the game. Walks have surged and games have grown longer, but attendance has actually risen, presenting a mixed picture. The Associated Press reported a comprehensive analysis of data from the first month of the season on Friday (Korea time).
MLB adopted the ABS challenge system this season. The most notable change since its introduction has been the strike zone. During the first month after Opening Day, the share of pitches landing inside the strike zone was 47.3%, down 3.3 percentage points from 50.6% during the same period last year. Walks rose 7.3% year-on-year. The AP reported that "if the current trend continues through the end of the season, it would produce the highest walk totals since 2000 and the ninth-highest in MLB history."
The ABS strike zone is individually calibrated to each batter's physique. Analysts attribute the shift to pitchers needing time to adjust to the new standard after adapting to the inconsistent zones called by home plate umpires. Jed Hoyer, president of baseball operations for the Chicago Cubs, said, "We saw the same phenomenon in the minor leagues," adding that "ultimately, it's something everyone will have to adjust to."
Driven by the increase in walks, the average game time has lengthened by five minutes, from 2 hours and 37 minutes last year to 2 hours and 42 minutes this year. The game times shortened by the 2023 introduction of the pitch clock have now stretched out again.
Despite the longer games, fan response has been positive. Average attendance in the first month rose about 2.8% to 28,545, up from 27,744 last year. Analysts say the ABS challenge itself has established itself as a new attraction. Strikeouts per game also edged up to 16.9 from 16.6, and average team runs climbed to 9.0 from 8.7, reinforcing an offense-driven trend.
In the opening month, 1,928 ABS video reviews were conducted. Of these, 1,030 calls (53.4%) were upheld. Challenge success rates varied sharply by position. Catchers succeeded on 605 of 997 challenges (60.6%), the highest rate, while batters were successful on 409 of 890 (46%), and pitchers on just 17 of 41 (41.5%). Catchers receive pitches directly behind the strike zone, giving them the closest view of the call, and because the result does not directly affect their personal statistics, they are able to make more dispassionate judgments.
Individually, Seattle Mariners catcher Mitch Garver posted the highest success rate, winning 10 of 11 challenges. Houston Astros catcher Christian Vazquez, by contrast, succeeded on only 4 of 13, the lowest rate. Among position players, Los Angeles Dodgers outfielder Teoscar Hernandez went 4-for-4, while Miami Marlins catcher Agustin Ramirez went 0-for-5.
Umpire accuracy was also disclosed. Willie Traynor had the highest accuracy at 95.3%, while Paul Clemons had the lowest at 91%. MLB's ABS operates as a "challenge" system, in which the home plate umpire makes the initial call and video review is used only when a challenge is filed. Each team can file two challenges per game during regulation innings. That operating philosophy differs from the Korea Baseball Organization (KBO), where every pitch is called using ABS.
One month into ABS implementation, the challenges of more walks and longer games have emerged, but so have positive signals of rising attendance and higher scoring. Attention now turns to how the numbers will shift in the second half and beyond, as pitchers continue to adjust.
