ABS 2026

The most important news in Major League Baseball right now is obviously the utter annihilation of those foul cheaters in Houston by the Seattle Mariners, all but insuring them not only a playoff appearance but their first AL West title in (mumble mumble) years. But another important announcement just dropped:

Major League Baseball will implement a challenge system for balls and strikes in the 2026 season after the league’s competition committee voted Tuesday to usher in the era of robot umpiring.

Following years of testing in the minor leagues, as well as during spring training and at this year’s All-Star Game, MLB forged ahead with a system that will give teams two challenges per game.

Hitters, pitchers and catchers will be the only ones allowed to trigger the system by tapping their head, and if a challenge is successful — the pitch will be shown on in-stadium videoboards — teams will retain it.

The ABS system uses similar technology to the line-calling system in tennis, with 12 cameras in each ballpark tracking the ball with a margin of error around one-sixth of an inch. The ABS zone will be a two-dimensional plane in the middle of the plate that spans its full width (17 inches). The zone’s top will be 53.5% of a player’s height and the bottom 27%.

Teams that run out of challenges over the first nine innings will be granted an extra challenge in the 10th inning, while those that still have unused challenges will simply carry them into extras. If a team runs out of challenges in the 10th, it will automatically receive another in the 11th — a rule that extends for any extra inning.

During the league’s spring training test this season, teams combined to average around four challenges per game and succeeded 52.2% of the time, according to the league. Catchers, whose value in framing pitches outside the zone to look like strengths could take a hit due to the new rule, were the most successful at a 56% overturn rate, while hitters were correct 50% of the time and pitchers 41%.

MLB’s minor league testing, which started in 2021, led to Triple-A players in 2023 using ABS challenge three days a week and a full ABS system, with every pitch adjudicated by computer, the other three.

Support grew around the challenge system among league executives as the more palatable of the two for fans, allowing for umpires still to play a role in balls and strikes but to have a backup system in case of blown calls in integral moments.

Some baseball fans seem to use their baseball fandom as safe way to be a reactionary nostalgic conservative, an impulse I’ve never been terribly sympathetic to. The suite of rule changes from a few years ago, particularly the pitch clock, have been an overwhelming success. As a Mariners fan who spends much of the season in Eastern Standard Time, and has a day job that often early morning obligations, the ~30 minutes shorter games have been a godsend. I was skeptical about shift restrictions but I’ve come around on that; I still don’t love the ghost runner in extra innings but I’ve made my peace with it; I now find objectionable almost entirely in theory, rather than in practice.

But this is huge. As a fan I find it absolutely maddening when excellence at strike zone judgement (for hitters) and control (for pitchers) is undermined by wholly unnecessary human error. While I get annoyed at umpire error, this isn’t an anti-ump thing; I think we should appreciate that they’ve consistently, steadily, improved their accuracy in the statcast era. But there’s a limit to their accuracy. As it stands, players are rewarded for their ability to manipulate and deceive the umpire, rather than their command of the zone. I appreciate and have some sympathy for the “just use robot umps for balls and strikes” position, and I’m open to the argument that would be even better. But I don’t hate the new element of strategy this creates in deciding to challenge, and how this rewards excellence in zone judgement in a new way. But even if I were convinced full-time robot calls is even better, this is a huge improvement over the status quo.