2024 MiLB Rule Changes: New Triple-A Strike Zone, Pitch Clock Tweaks And More

For 2024, the experimental rules across the minor leagues won’t change dramatically from 2023, but there will be some tweaks, Baseball America has learned.

The biggest changes will be the continued attempts to tweak and improve the automated ball-strike (ABS) strike zone. MLB will be running two different types of measurement for ABS for Triple-A and the Low-A Florida State League.

But there also will be tweaks to the pitch clock, pitcher disengagement and other rules.

Automated Ball-Strike/Strike Zone Tweaks

The ABS system experiments will continue in Triple-A and in nine of the 10 parks in the Florida State League (all but Daytona).

For Tuesday-Thursday games in Triple-A and the ABS-equipped FSL parks, the ABS system will call all pitches. The home plate umpire will relay the call after hearing it in their earpiece. The ABS challenge system will be in effective for Friday through Sunday games. The home plate umpire will call pitches, but the batter, pitcher or catcher can appeal their strike call. The ABS system will then rule on whether the call stands or is overturned. Each team gets three unsuccessful challenges per game. Successful challenges do not count toward that total. All challenges must be made within two seconds of the call.

MLB is providing teams in these games with an iPad that will show the tracked location of each pitch on a few seconds delay, and is asking the teams to flag pitches that they believe are questionable calls, which could help lead to further tweaks to the strike zone used in ABS games.

The strike zones for Triple-A and the Florida State League will be different. In Triple-A, the strike zone will be 17-inches wide (the width of the plate) with a two-dimensional rectangle at the midpoint of the plate. The top and bottom of the strike zone will be set at 53.5% and 27% of the batter’s height. While the width and bottom of the zone are the same as last year, the top of the strike zone has increased by 2.5%.

Last year, the strike zone was deliberately lowered at the top to reduce the number of swings and misses on high fastballs. However, that adjustment inadvertently resulted in a significant rise in walks, outweighing any decrease in strikeouts.

In the International League, runs per game increased by .52 (4.98 to 5.50), while walks increased from 4.0 to 4.8 per nine innings and hits increased from 8.7 to 9.0 per nine innings. The strikeout rate remained flat at 9.2 per nine innings.

In the Florida State League, the zone will be quite different. Most importantly, the width of the zone in the FSL will be 20 inches (three more than in Triple-A). Like Triple-A, it will be measured as a rectangle set at the middle of the plate.

The top and bottom of the zone will use the Hawk-Eye visual tracking system. The bottom of the zone will be set to the height of a hitter’s back knee, while the top of the zone will be set based on the midpoint of a batter’s hips, with the goal of making the top of the zone equal to one baseball above a batter’s belt. If a hitter’s stance changes, the strike zone will change as well, but it will be based on a rolling median of the hitter’s stance on previous pitches that have been put in play. So a hitter who tries to manipulate the zone by taking pitches but not swinging from an exaggerated crouch will not be rewarded.

Pitch Clock Rules Adjustments

The pitch clock adjustments will be minor. The key development is the pitch clock is now going to be uniform across the majors and minor leagues. At all levels of full-season baseball, there will be an 18-second pitch clock with runners on base, a 15-second pitch clock with no runners on, and a 30-second pitch clock between batters. Inning breaks and pitching changes will have a two-minute, 15-second pitch clock.

Last year, the pitch clock was 19 seconds in Triple-A, 18 seconds in Double-A and below and 20 seconds in MLB. There is also no enhanced grip baseball test this year, unlike last year when the Double-A Southern League used a stickier baseball in the first half of the season.

If a pitcher makes a pickoff throw, steps off the rubber or feints a pickoff throw with a runner on base, it counts as a disengagement. Pitchers are allowed two disengagements per plate appearance (a pitcher can throw over a third time, but it counts as a balk if the baserunner is not retired on the pickoff attempt).

There is one tweak to this rule in the minors. This year, the disengagement count resets if a baserunner advances. Last year, it was not. So if a pitcher has thrown over twice and a baserunner then steals second base on the following pitch, the pitcher will once again have two disengagements to use.

If a pitching change occurs during an inning break, and the incoming pitcher does not step onto the warning track until there are less than two minutes remaining on the pitch clock, the pitch clock will be reset to two minutes. Umpires have the right to waive off this reset if they determine that the pitcher has deliberately delayed their arrival.

If there’s a foul ball, the 2024 rules will have the pitch clock operator reset the pitch clock and begin the timing once the fielders, baserunners and batter have returned to their previous positions and the pitcher has the ball and is near the mound. Last year, the rule required the pitcher to step onto the mound before the pitch clock began to count down again.

Complex leagues will not use the pitch clock in 2024. They didn’t use it in 2023, either. Teams can run a clock to help players get used to it, but pitch clock violations won’t be called. The complex leagues will use the limits on pitcher disengagements and batter timeouts.

Pitching Substitution Tweak

In 2024, a pitcher who warms up has to face one batter, even if the batting team replaces the scheduled batter with a pinch hitter. In the past, a team could delay making a pitching change until the batter was officially announced, and then make a pitching change before the first pitch of an inning was thrown.

Mound Meetings

Complex leagues, Class A and Double-A teams are allowed seven non pitching change meetings per game. At Triple-A, teams are allowed five non pitching change meetings per game. Unlike the major leagues, Triple-A teams will not get an extra meeting in the ninth inning if they have used all of the allotted meetings before then.

Big Bases

The 18-inch bases that were adopted last year will be used at all U.S. minor league levels and are encouraged (but not required) in the Dominican Summer League.

Infield Shifts

The infield positioning (anti-shift) rules for the major leagues will also be enforced throughout the minor leagues. Teams must have two infielders on either side of second base and all infielders must be positioned on the infield dirt. Players may not switch positions from one side of the infield to the other during an inning unless a new defensive player enters the game (a pitching change does not count for purposes of a player swapping sides).

PitchCom

PitchCom (the system by which catchers send signals by a device instead of signs) will be used in Triple-A, but in a more limited manner than in the major leagues. Each team will have one transmitter and four receivers. Only the active pitcher, active catcher and a pitcher warming up are allowed to use the receivers, and only the active catcher can use the transmitter.

Runner’s Lane/Obstruction

The runner’s lane and emphasis on umpires calling the obstruction rule that have been adopted for the major leagues will also be applied to the minor leagues. The one difference with the runner’s lane rule in the majors is MLB teams must ensure that the distance from the foul line and the cut of the grass in fair territory is between 18 and 24 inches. That measurement will not be enforced in the minor leagues, but umpires will be instructed that a baserunner is acceptably in the runner’s lane if both of the player’s feet are in the dirt when the runner crosses the 45-foot mark between home plate and first base or when the fielder releases their throw, whichever is later.