Diamondbacks did not make the most out of ABS challenges in its debut season

Major League Baseball made a monumental rule change for the 2026 season, and the Arizona Diamondbacks were among the most accurate teams at using the new Automated Ball-Strike challenge system.

The D-backs were also one of the least aggressive clubs when it came to tapping helmets.

Arizona went into the year with some clear guidelines on handling the new tool for players to overturn incorrect calls made by the home plate umpire. Teams start with two challenges and keep them if correct, with only the pitcher, catcher and hitter allowed to call for one.

D-backs pitchers were not supposed to challenge to avoid emotional decisions, and the team stressed that it needed a challenge available to use late in the game.

“What I tell these guys is, if you are 100% certain, you can go at any time, but you better be 100% certain,” manager Torey Lovullo said last month. “That’s what we’re trying to figure out, that part of the equation. Because they think they know and they don’t. We still gotta get better at it.”

Diamondbacks ABS challenges, by the numbers

Overall, 54% of challenges made league-wide were overturned, 49% from hitters and 58% from defenders.

The Diamondbacks finished the year with a 60% win percentage on ABS challenges, third in MLB behind only the Cincinnati Reds (62%) and Athletics (60%).

Arizona’s 308 challenges were the 27th most in the sport, however, with an average of 1.90 per game. Only five teams averaged fewer than two ABS challenges each game, as too many times this season the Diamondbacks took theirs home with them.

In terms of challenge rate, Diamondbacks hitters were 29th and fielders (nearly exclusive to catchers for Arizona) 24th. On both sides of the ball, the D-backs were bottom 11 in MLB in flipping strikeouts and walks, signaling a need to evolve moving forward.

By Baseball Reference’s leverage index, the Diamondbacks generally executed their plan of saving challenges for more important moments of a given game.

There was a clear adjustment period for veterans, while youngsters who had experience using the ABS system in the minor leagues may have been more careful not to waste challenges for the experienced players.

The most infamous example of Arizona letting a potential challenge go was on July 18. Ketel Marte did not tap his helmet after a called third strike on a pitch outside the zone to end a game against the St. Louis Cardinals despite having two left.

“I was looking for a breaking ball,” Marte said at the time. “Got the two-seamer and I was a little bit surprised.”

Unsurprisingly, Arizona’s most aggressive challenger was shortstop Geraldo Perdomo, who was famously rung up on a pitch below the knees to end the Dominican Republic’s run in the World Baseball Classic.

Perdomo has a very keen eye at the plate and set a career high in walk rate, so it was surprising that Perdomo was one of the least accurate challengers on the team at 48%. His 33 ABS challenges were the eighth most in the league this past season.

Catcher Gabriel Moreno won 68% of his challenges as a batter and 62% on defense, arguably the most impactful challenger on the team. Nolan Arenado and Corbin Carroll were both over 70% but used their challenges sparingly (22 combined).

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