The minor league season will not start until the first week of May, but when it does start, there will be some rule changes implemented at various levels to allow MLB to observe the impact of those rule changes on the game.
At the AAA level, bases will be increased in size from 15 inches square to 18 inches square. This is done to reduce the chances of collision, though the announcement indicates the expectation is that the reduced distance between bases could result in a slight increase in hits and successful steals.
At AA, the defensive team must have at least four infielders, all of whom must have both feet in front of the outfield dirt boundary.