Monday, Fangraphs’ Eric Longenhagen wrote about several experimental rule changes that will be used in some of the minor leagues this year.
The key here is “experimental.” Don’t expect all of these to be instituted in MLB, and even for some that might be, I would think testing will go on for several seasons.
So let’s take a look at them.
The first, which I won’t quote extensively here, is going to be used only in rookie-level and lower leagues — the Arizona Complex League, Florida Complex League and the Dominican Summer League. This rule change will allow the starting pitcher to re-enter the game after being removed, subject to the following restrictions:
- Only the starting pitcher may reenter the game after being removed.
- The removed starting pitcher may only reenter the game at the beginning of the inning following removal and may only reenter the game once.
- To be eligible for re-entry, the starting pitcher must throw at least 25 pitches in the inning during which he is removed.
COMMENT: A process like this has existed in Spring Training over the last few years, when a team wants a pitcher to throw a certain total number of pitches but not too many in one inning. It’s used when a pitcher has given up a lot of hits or walks or runs in an inning and the manager just wants to get the inning over with, then have the starter come back and finish his allotted pitch count. Longenhagen concludes:
This is the first rule change listed in the memo, but it’s also the only one that seems like it’s being implemented solely with player health and development in mind and isn’t being piloted for eventual big league use.
So just make a note of this, you won’t be seeing this in MLB. Now, on to some you might see in MLB someday.
Games played in the Pacific Coast League will use the ABS Challenge system and follow the same rules that have been adopted at the Major League level for the 2026 season (i.e., each team will start the game with two challenges, successful challenges will be retained, teams will receive an extra challenge if they have no challenges remaining in extra innings, etc.). Consistent with past seasons, MLB will monitor gameplay to determine if there is a desire to test changes at a later point in the season. Beginning on May 5, 2026, the batter, pitcher, or catcher may also appeal the umpire’s decision regarding whether the batter swung at a pitch (“Check-Swing Challenge”). A swing will be considered to have occurred if the maximum angle between the bat head and the bat handle exceeds 45 degrees. This rule was tested in the Florida State League and Arizona Fall League in 2025. In the FSL, the strikeout rate was over 3% lower when Check-Swing Challenge was used, having a positive impact on balls in play and encouraging more extensive testing at higher levels. Under this format, each team will continue to start the game with 2 challenges. Challenges may be used on either ball/strike calls or swing/no-swing calls, but not both on the same pitch.
This will also be used in the other Triple-A league, the International League, as well as in the Florida State League.
COMMENT: The check-swing review was used on a limited basis in the Arizona Fall League last year, as noted. It seemed well-received, because it did make a specific note as to exactly what is considered a check swing, something that’s not now in the rule book and so is up to the umpire’s judgment. It will be interesting to see the results of this experimental rule. I’d think that after testing this might come to MLB, but it will take a few years. There are a couple of videos in the Fangraphs article where you can see this in action.
PitchCom Safe Harbor. In Triple-A, teams will be assessed a mound visit if play is stopped for the purpose of addressing an issue with PitchCom (at which point the team will have the opportunity to address the issue while the Pitch Clock is turned off). If the team does not have a mound visit remaining, a Pitch Clock Violation will be assessed (i.e., automatic ball), at which point the team will have an opportunity to address the issue while the Pitch Clock is turned off.
COMMENT: This seems kind of extreme for something that is a technical issue, not something teams are using to delay games. Or does MLB think the latter is actually what some teams are doing?
Defensive Signals. At all levels, the clock will no longer stop and reset when the catcher leaves his position to give defensive signals. If the catcher is unable to return to the catcher’s box with at least 9 seconds remaining on the clock, a Pitch Clock Violation will be assessed (i.e., automatic ball).
COMMENT: I’m not sure how often you see a catcher do this. It will be interesting to see how this works in practice.
Mound Visits. At all levels, mound conferences must end and all coaches and players, other than the pitcher, must be off the dirt of the mound and moving toward their positions or the dugout before the mound visit clock reaches zero. Failure to comply with these requirements will result in a Pitch Clock Violation (i.e., automatic ball).
COMMENT: This is something you see all the time in MLB games. The mound visit clock starts at 30 seconds. The umpire usually starts heading to the mound to break up the conference with a couple of seconds left on the clock, and often the manager/coach and players dilly-dally a bit. This is a way to attempt to speed up games after mound visits. I could get behind this.
There are several experimental rules for batter timeouts, depending on the minor league level.
Double-A & Triple-A. When a batter requests time, the home plate umpire will grant time, point at the batter, then immediately reset the Pitch Clock. Batters must return to the batter’s box and become alert to the pitcher before the clock reaches 8 seconds remaining.
High-A. Batters will only be permitted to request time with runners on base (i.e., batters will not be permitted to request time with the bases empty). Umpires may continue to grant time if a special circumstance applies (e.g., hitter is brushed back, there is bona fide equipment issue, or injury concern).
Single-A. Batters will not be permitted to request time. As in High-A, umpires may continue to grant time if a special circumstance applies (e.g., hitter is brushed back, there is a bona fide equipment issue, or injury concern).
COMMENT: In MLB games now, you almost always see hitters request a timeout with two strikes on them, to be able to reset a bit. Occasionally, they’ll do so with fewer than two strikes. To eliminate them completely seems excessive. The Double-A and Triple-A rule above might work. I don’t think batter timeouts under the current system delay games too much.
Disengagement Limit. In Double-A, the Disengagement Limit will be reduced from 2 to 1. When there are runners on base, pitchers may pickoff or step off once during a plate appearance without penalty. If they disengage a second time and all runners return safely, time will be called and all runners will be advanced one base. Consistent with the Disengagement Limit used at other levels of play, if a runner advances a base during a plate appearance (e.g., stolen base), the Disengagement Limit will reset.
COMMENT: This will basically super-charge stolen bases in the Double-A level. If that’s what MLB wants, then… we’ll see if the results of this test are such that they’d want to use it at higher levels.
To encourage more action on the bases, in the International League second base will be placed entirely within the perimeter of the infield diamond during the second half. This change will decrease the distance between first base and second base, and the distance between second base and third base, by approximately 9”, i.e., double the change achieved by increasing the size of the bases from 15” inches to 18.” MLB will work with the groundskeepers in the International League to move second base prior to the start of the second half of the 2026 season.
COMMENT: This will have the effect of allowing slower runners to go from first to third on a single, or perhaps score from first on a double, bu decreasing the actual amount of distance they have to run to do that. Again, it will be fascinating to see the results of these tests.
Remember, all of these are being deemed “experimental,” so it’s entirely possible they toss all of these after the experiments. In any case, since they’ve been tweaking the rule book over the last few years, it generally takes several years and lots of testing before any such changes are made at the MLB level. It’ll definitely be worth watching the minor leagues indicated to see how these rule change ideas work in practice.
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