The 2026 MLB season saw the implementation of the automated ball-strike system, which allowed batters, pitchers and catchers to challenge balls and strikes during the game. Let's take a look at some of the best and worst uses of ABS in its inaugural season, from highly successful individual players to challenges that were off by 7 inches or more.
All data is updated through the 2026 Regular Season.
Best teams at ABS challenges
The Cincinnati Reds were the most successful team overall, getting 61.6% of their challenges correct. The MLB average is 54%.
The Arizona Diamondbacks were the best when their batters challenge, with 56.9% of those challenges correct. The MLB average is 49%.
The Philadelphia Phillies were the best at challenging on defense. When their pitchers/catchers challenged they were correct 69.4% of the time. The MLB average is 58.0%.
Worst teams at ABS challenges
The Pittsburgh Pirates ended up the least successful team overall, getting 47.0% of their challenges correct. They were one of five teams under 50% on the season.
The Atlanta Braves, at 41.7%, were the least successful at having their batters challenge, with the Seattle Mariners not far behind.
The Chicago White Sox were the least successful challenging on defense. Their pitchers/catchers got just 49.3% of challenges correct -- the only team under 50% in that category.
Most successful players at ABS challenges
Sal Stewart of the Reds had by far the most successful challenges at the plate this season with 28; nobody else has more than 21. In terms of challenge percentage, among players with at least 20 challenges at the plate, Gabriel Moreno of the Diamondbacks had the best success rate, getting 17 of 25 correct (68.0%).
Behind the plate, it was William Contreras of the Brewers with the most successful challenges as a catcher with 105. He challenged 185 pitches, which is 49 more than any other player. In terms of challenge percentage, among catchers with at least 50 challenges behind the plate, the Phillies' J.T. Realmuto was the most successful, converting 70 of 86 (81.4%). The next-closest player, Salvador Perez of the Kansas City Royals, was at 70.8% correct.
Challenges by pitchers became increasingly rare as the season progressed. Drew Anderson of the Tigers had the most successful challenges from the mound with five. His eight total challenges as a pitcher were tied with Freddy Peralta for the most in the league. The only pitcher to challenge multiple pitches and get them all correct this year is Chris Bassitt of the Baltimore Orioles, who went 2-for-2.
Least successful players at ABS challenges
Among players to challenge at least 20 times at the plate, it's a tie for the worst success rate. Ceddanne Rafaela of the Red Sox and Willi Castro of the Rockies both went 6-for-24 (25%) on the season.
Among catchers to challenge at least 50 times behind the plate, Drew Millas of the Nationals had the lowest success rate, converting 22 of 51 challenges (43.1%) successfully. The next-worst catcher was 46.7%.
Plenty of pitchers didn't get any challenges right this season, but it was Cristopher Sanchez of the Phillies who was the most unsuccessful, going 0-for-5 on the year. The Orioles' Yennier Cano was the only other pitcher to challenge more than twice without getting any correct (four times).
Most egregious individual challenges
There were a lot of very close calls challenged... and others not so much. Here's a look at the challenges on the pitches farthest off the plate, both inside the zone and out.
Most egregious called strikes overturned to balls
These were called strikes before a successful batter challenge.
Most egregious balls overturned to strikes
These were called balls before a successful pitcher/catcher challenge.
Umpires
Among the umpires with at least 100 pitches challenged, Jansen Visconti had the lowest percentage overturned at 41.7%, or 43 of 103. On the reverse side, Andy Fletcher saw 81 of 122 challenged pitches (66.4%) overturned.
Among umpires with at least 5,000 pitches called this season, Erich Bacchus had the lowest percentage challenged with 1.07% of the total pitches seen (99 out of 9,224). Hunter Wendelstedt had the highest rate with 1.92% (167 out of 8,683 pitches).