MLB's pitch clock and other recent rule changes explained, including the ABS challenge

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Major League Baseball changed more in a few seasons than it had in decades. Games are shorter, there are more stolen bases, and in 2026 players can challenge ball and strike calls using tracking technology. If you are returning to baseball after some years away, or are new to it, here is what changed and why.

The pitch clock

Introduced in 2023, the pitch timer is the change fans notice most.

15 seconds with the bases empty. The pitcher must begin his motion before the clock runs out.
18 seconds with runners on base. This was 20 seconds in 2023 and was cut to 18 from 2024.
The batter must be in the box and alert to the pitcher by the eight-second mark.
Violations cost a pitch. A pitcher who is late is charged an automatic ball. A batter who is not ready is charged an automatic strike.
There is a timer between batters too, so the next hitter cannot linger.

Average game times fell sharply after the clock arrived, and games now move with far fewer long pauses.

Limits on pickoffs and step-offs

Pitchers are allowed two disengagements per plate appearance, meaning pickoff attempts or stepping off the rubber. If a pitcher tries a third pickoff and fails to get the runner, the runner moves up a base. The count resets if a runner advances. This gives runners more freedom to take a big lead.

Bigger bases

First, second and third base grew from 15 inches square to 18 inches square in 2023. The bases are slightly closer together as a result, which helps runners a little and reduces collisions and injuries around the bag. Together with the pickoff limit, it led to a clear rise in stolen bases.

Limits on the defensive shift

Since 2023, teams must have two infielders on each side of second base when the pitch is thrown, and all four infielders must have both feet on the infield dirt. Teams can no longer put three infielders on one side or station an infielder in short right field. More ground balls find holes, which especially helps left-handed pull hitters.

The ABS challenge system in 2026

After years of testing in the minor leagues and in spring training, the Automated Ball-Strike challenge system arrived in the major leagues in 2026.

Human umpires still call every pitch. Technology does not call balls and strikes on its own.
Each team starts with two challenges per game. A successful challenge is kept, so a team that is right can keep challenging.
Only the pitcher, catcher or batter may challenge, with no help from the dugout. The player taps his cap or helmet immediately after the call.
The tracking system checks the pitch against a strike zone set for that batter, and the result is shown on the stadium screen within seconds.
Extra innings bring an extra challenge for a team that has used both.

Because only close calls are challenged, catchers who are good at framing borderline pitches still have value.

Older changes worth knowing

The universal designated hitter arrived in 2022, so pitchers in both leagues rarely bat.
The automatic runner in extra innings starts each half-inning from the tenth with a runner on second base, made permanent in 2023.
The three-batter minimum from 2020 requires a relief pitcher to face at least three batters or finish the inning.
Intentional walks need no pitches. The manager signals and the batter goes to first.

Which rule change do you like or dislike most? Share your thoughts and questions in the comments.