Milwaukee Brewers catcher William Contreras won the 2026 World Series MVP award after helping the club beat the Tampa Bay Rays in five games for its first championship. He hit .381, drove in four runs and threw out four attempted base stealers. Yet one of his most distinctive contributions came from baseball’s new automated ball-strike challenge system: Contreras overturned 10 calls during the series.

The 28-year-old was one of the first players to make the technology a defining part of a World Series performance. Major League Baseball introduced the ABS Challenge System this season, allowing batters, pitchers and catchers to appeal a ball-or-strike ruling using Hawk-Eye tracking. Contreras’ record showed how quickly a skilled catcher could turn the tool into a competitive advantage.

Milwaukee clinched the title with a 4-1 victory in Game 5 on October 28. Contreras contributed an RBI double in the sixth inning while guiding a pitching staff that kept the Rays from mounting a sustained comeback. His four caught-stealing plays across the series further limited Tampa Bay’s running game.

A catcher who learned to challenge the strike zone

Under the 2026 rules, only the batter, pitcher or catcher can initiate an ABS challenge, and the request must come immediately after the call. Each club starts with two unsuccessful challenges available. The strike zone is measured using player height and the ball’s location at the middle of home plate, rather than a camera angle or a manager’s request.

Contreras led the regular season with 185 challenges and 105 successful overturns, according to Associated Press reporting. He then won 22 of 33 challenges in the postseason, including 10 of 13 in the World Series. That 10-for-13 figure is the one reported by AP, Reuters and MLB; a separate CBS Sports report lists 10 of 14. The discrepancy does not change the documented 10 overturns, but the attempt count should not be treated as unanimous.

The system does not replace the plate umpire on every pitch. Officials still make the initial call, while limited player-initiated challenges trigger an electronic review. A catcher therefore has to combine traditional receiving and game management with the judgment to decide when a borderline pitch merits an appeal.

Milwaukee’s first title, with more than one hero

Contreras’ MVP case was not uncontested. Rookie Cooper Pratt delivered timely hits, Jackson Chourio batted .458 in the series, and Jacob Misiorowski pitched 5 2/3 scoreless innings in the deciding game. Milwaukee’s title was a team achievement, but Contreras supplied offense, defense and a new form of on-field decision-making at the same time.

The technological implications extend beyond this championship. MLB’s public ABS dashboard offers a way to track challenges and overturns across the league. Teams can study which players recognize the strike zone most accurately and whether challenge decisions improve over time. As with other forms of sports analytics, the competitive edge comes not from possessing the same technology as everyone else, but from using it better.

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