Arizona Fall League To Use Newly Approved MLB Rules

A pitcher must begin his motion before the expiration of the timer. Pitchers will have up to 15 seconds between pitches when the bases are empty and up to 20 seconds between pitches with at least one runner on base. 

One notable difference between the regular minor league season and the Fall League, however, is the absence of the disengagement (pickoff and step-off) rule. During the regular year, pitchers were allowed to step off the rubber or attempt to pick off a runner just twice. If a third attempt was made unsuccessfully, the move constituted a balk and the runner was allowed to take the next base.

Defensive shifting will also be greatly limited. Now, teams must have at least four players on the infield—two on either side of second base—with both feet on the infield’s outer boundary. In other words, there will be no more extreme shifting to the pull side. 

The bases will be larger, too, with first, second and third base growing from 15 to 18 inches square. The idea is to prevent injuries on collisions at the bag and to promote more stolen base attempts. These larger bases were in use in the minor leagues this year as well. 

Finally, the automatic ball-strike challenge system will be in play for games at Salt River Field and during the league’s scheduled tripleheader on Oct. 15 at Chase Field, the big league home of the Diamondbacks. In past years, games at SRF were called exclusively by the ABS. Now, the games will be called by the human umpires, but each team will get three challenges per game, though a team will keep its challenge if it is successful. 

To contest a ball-strike call, a team will inform the home plate umpire of its intent to challenge his call. The umpire will then receive the ABS’ ruling, which will confirm or deny his call. If the ABS disagrees with the human umpire, he will change his call on the field. 

This system was in play in select Triple-A parks during the 2022 season.