I was always under the impression that a false start is called if a player moves after being set before the ball is snapped. But often-times when the QB is calling an audible, you see linemen turn around to hear him, RBs walk up a few steps to listen, and everyone generally moving around a lot more than they do when they get false start penalties. What makes one sort of movement a false start, while the other is ignored?
WAG - simulation of the start of a play.
I was sorta thinking something like that too (and it may be the right answer), but seeing the RBs step forward to listen like that would make me think the play was starting if I was a defender.
Or maybe I’m just being stupid, and everyone on the field hears the QB calling an audible, and the refs give the players some leeway to listen.
With the exception of a man legally in motion and the center (who has to move to snap the ball) the entire offense must be observed in a set position before the ball is snapped. If they move to hear an audible they must be observed to reset their position when the ball is snapped.
Generally, a running back will move forward and then reset. Linemen will tilt/twist/point, but they hold their ground.
There is some courtesy in the NFL, as I’ve not witnessed this type of twisting and moving to hear during an audible concocted in such a way to fool anyone. And, if it did, it’d be a penalty.