Can they please stop?
Tell me I'm not alone with this.
It doesn't always have to gain much, if any, yardage, although you obviously don't want to lose yardage on any play. But I'm sure they run it to make the DC consider Pig as a 2nd or 3rd RB in the backfield on certain formations. When the D sees the offense in a certain formation with Pig in particular spots, they will anticipate Pig on a reverse. It helps open the middle of LOS for Neal/lane, or for Dobbs to keep it and go away from Pig. So they will run different plays off the same set to keep the defense different things to think about, and Pig on the reverse is one of them.