World Baseball Classic rules, explained: The biggest differences vs. MLB, including pitch counts and run limits

Baseball's finest talents will dance in the spotlight one month before Opening Day.

Whereas this part of the baseball calendar typically revolves around MLB's spring training, the 2026 season sees a fan favorite return to the fore: the World Baseball Classic.

Its competitors are expected to sparkle. Samurai Japan is the defending world champions, having vanquished all comers -- including the United States -- to claim its third WBC crown.

Cuba, Dominican Republic, Puerto Rico and Venezuela are also expected to flash, as are those pesky Americans, who boast perhaps the competition's best lineup.

The WBC will not merely be marked by the quality of the players set to take the diamond over the next two weeks. It will also be defined by its rules, which bear more than a passing resemblance to its MLB counterpart.

Here's what you need to know about the edicts set to take center stage during the 2026 World Baseball Classic.

MORE: Full list of players for 20 teams competing in 2026 World Baseball Classic

World Baseball Classic rules

Pitcher usage rules

Pitching has proven increasingly volatile for the game's starters. Injuries strike the sport's finest talents, leaving them sidelined for months on end.

The World Baseball Classic takes that dynamic into account, calling for limits on pitcher usage throughout the tournament.

The action will be contested throughout spring training, leaving players -- particularly pitchers -- susceptible to injury in the event of overuse. The WBC's rules work to limit pitcher ailments, although its impossible to entirely curb the threat.

Here's a look at the pitching rules for the World Baseball Classic, separated by each round. They are as follows:

• Maximum 65 pitches in one game during pools
• Maximum 80 pitches in one game during quarterfinals
• Maximum 95 pitches in one game during semifinals and the championship.
• Minimum four days rest after a 50-pitch game.
• Minimum one day rest after a 30-pitch game.
• No pitching three straight days under any circumstances.

Rest days should prove paramount throughout the tournament, especially for sides with deeper bullpens than most. Expect fireworks as starting rotations give way to relievers.

MORE: Ranking the 2026 WBC teams from best (USA) to worst (Czechia)

Three-batter minimum

Pitchers are required to face off against at least three batters before departing to the dugout. MLB implemented the same rule in 2020 amid calls to improve the sport's pace of play.

Universal DH

The universal DH is in effect for the World Baseball Classic. It's something of furniture in the big leagues, having come into play ahead of the 2022 season.

The edict should help spark increased offense throughout the tournament. Standouts like Kyle Schwarber, Alfredo Despaigne, and, most notably, Shohei Ohtani, should get the chance to set the stands alight across the two-week spectacle.

Extra innings runner

The extra innings runner on second has been referred to by many kitschy names. "The zombie runner," "the ghost runner," and "the Manfred runner" have all been used. Henceforth, it will be referred to here as the Manfred runner, but it may go by other names.

Just like MLB, there will continue to be a runner on second to start each extra inning in order to help keep games a reasonable length.

MORE: World Baseball Classic rosters by MLB team

Replay

Replay review is a part of the World Baseball Classic, operating in the same fashion as its MLB counterpart. Managers will be permitted to request one review per game in pools and quarterfinals. That figure goes up to two during the semifinals and final.

Mercy rule

The mercy rule is the largest -- and perhaps the most controversial -- difference between the bigs and the World Baseball Classic. The statute is similar to the one used in Little League, albeit with different values in different innings. If a side is up 15 or more runs after five innings or 10 or more runs after seven innings in pool play, the game will be called.

This decree will vanish following pool play. Sides can attempt to scale double-digit gulfs during the knockout stages. 

Larger bases, pitch clock, and infield shift ban

MLB enacted a trio of new mandates ahead of the 2023 season, introducing larger bases, a pitch clock and a ban on infield shifts in the hopes of spurring an improved pace of play.

Those proclamations remain in effect three years later. The WBC opted against following suit ahead of its 2023 competition. In 2026, the pitch clock will come into play, with pitchers granted 15 seconds to fire arrows towards their catcher with the bases empty and 18 seconds when runners are on.

Bases will retain their traditional 15-inch dimensions during the 2026 World Baseball Classic, while defenses will be permitted to shift any way they see fit.

MORE: Expert picks, odds and favorites for 2026 WBC tournament

Automated Ball-Strike

MLB is rolling out the Automated Ball-Strike challenge system during the 2026 season, giving players the opportunity to contest strike-zone judgements from home plate umpires via the replay system. That won't be the case in the World Baseball Classic, however; the tournament opted against the spurned the precept, with organizers arguing its implementation could bring about competitive imbalances.