Which Teams Used The New ABS Challenge System Most (And Least) Effectively This Spring?

Major League Baseball is implementing the new Automated Ball-Strike (ABS) Challenge System starting in the 2026 season. The Statcast data from Baseball Savant provides several visualizations of the results of these challenges.

There is surface-level data that offers interesting insights into which teams are most and least successful, as well as which players stand out the most. There is also detailed data that indicates behavioral aspects of challenging. These observations should come with an important caveat: spring training data may reflect players pressing to make Opening Day rosters. It will be interesting to compare how challenge behaviors change (if at all) once the regular season begins.

ABS Challenge Rates

Baseball Savant defines challenge rate as “the rate of challenges initiated out of potential challenges, defined as non-swings (takes) that a) came with at least one challenge available and b) resulted in calls that went against the challenging team (i.e., called strike for hitters and called ball for fielders).”

Batters tend to challenge at a higher rate than catchers, and they are more likely to challenge in high-leverage situations. For instance, batters have an overall challenge rate of 4.8%, which jumps to 17% and 20% on two-strike and full counts, respectively.

Throughout spring training, batters saw significant variation in challenge rates. Batter challenges peaked on March 3 with a seven-day rolling average of 6.3%. By March 24, that rolling average dropped to 4.0%. This could suggest hitters were still calibrating to the ABS strike zone early in camp. 

Catchers have a 2.3% challenge rate and have not been as sensitive to high-leverage counts. Their challenge rate did not meaningfully jump for two-strike counts, but increased to 4.1% and 5.5% for three-ball and full counts, respectively. Unlike hitters, catchers’ seven-day rolling average stayed relatively steady between 2.0% and 2.5% throughout March. 

ABS Challenge Success Rates

The overall success rate of challenges is 53%, but the success rates for catchers and hitters differ significantly. Catchers succeed 60% of the time, compared to 46% for hitters.

Both batters and catchers have overturn rates that diminish in these higher leverage counts. In full counts, success rates drop to around 43%. Either side in a loaded count stands to overturn a negative outcome and immediately flip the result. Changing a strikeout to a walk (or vice versa) can have a meaningful impact on the game state. 

Team Behaviors

Not every team challenges at the same rate. The New York Yankees have an aggressive challenge strategy, leading the league on both sides of the plate. They have a 9.0% hitter challenge rate and a 4.5% catcher challenge rate. On the opposite end of the spectrum, the Arizona Diamondbacks have the lowest combined challenge rates, at 2.3% and 1.5% for catchers and hitters, respectively.

Some teams favor one side of the plate. The Kansas City Royals batters challenge at 5.5% of the time (8th-highest), but as catchers, not as often at only 1.8% (7th-lowest). Conversely, the Atlanta Braves challenge often as catchers, at 2.9% of the time (4th-highest), and rarely as batters, at only 3.8% (7th-lowest).

While the Yankees have the most challenges, they do not have the highest success rates. The Phillies have the highest success rate for batters at 52%, and the Cardinals have the highest success rate as catchers at 75%. The Diamondbacks have the lowest batter success rate at 33%, and the Dodgers have the lowest catcher success rate at 43%.

Baseball Savant includes a chart that accounts for expected challenges based on pitch location, number of remaining challenges, runners on base, and the ball/strike/out situation. The Cardinals rate as the best team relative to expectation, with 12.8 more overturns than expected as catchers and 6.0 more overturns as hitters. Even though the Cardinals are near the middle of the pack in challenge rate, they have driven the most value from their challenges overall.

The Mets were the worst team on defense, with 6.4 fewer overturns than expected, while the Nationals were the worst team batting with 7.6 fewer overturns than expected.

When do teams issue their first challenge? It's no surprise that the Yankees are the quickest team to challenge. On average, they issue a first challenge around the 2nd or 3rd inning, and they are tied with the Chicago White Sox, who are not as aggressive in their challenges, but rank 9th and 5th for batters and catchers, respectively.

The team that is most patient with their challenges this spring was the Baltimore Orioles, who, on average, wouldn’t challenge until the 4th or 5th inning in games where they issued one.

When do teams usually run out of challenges? The Athletics ran out of challenges the soonest, around the 4th inning, in the six games they exhausted them. The Detroit Tigers only ran out of challenges three times, typically around the 8th or 9th inning.

The Yankees ranked 14th in earliest depletion time at around the 6th inning. It should be no surprise that they ran out of challenges the most often, with 20 game occurrences. The Twins ran out of challenges 19 times and ranked second overall in challenge frequency.

It is not a surprise that teams that challenge more often run out of challenges, but it is also noteworthy that those teams aren’t necessarily reckless, as they do not consistently lose those challenges early.

ABS Challenge Takeaways

It is clear that teams are implementing different challenge strategies throughout spring training as they get used to the ABS system. Will these trends continue into the regular season, or will teams maybe be more selective in their challenges when the games start to matter?

Entering the regular season, it would be interesting to see if win-probability implications could be added to the ABS data to see which teams and players have impacted their teams’ win probabilities based on their challenge success. Reversing a walk or strikeout in key moments can materially swing game outcomes, and teams could potentially use this information to determine optimal challenge strategies. While the volume of challenges doesn't necessarily drive success, it will be important for teams to strike a balance between taking advantage of the challenges available to them and not losing their valuable challenges too early in the game.