Man In Motion

[Alduflux]

What happens in the following scenario. 

Offense gets set.  A man goes in motion and is moving towards the LOS at the snap.  A flag is thrown at the snap.  The ball is handed off to the RB for a twenty yard gain.

My question is when should the official blow the whistle?

[Bobref]

1 hour ago, Alduflux said:

What happens in the following scenario. 

Offense gets set.  A man goes in motion and is moving towards the LOS at the snap.  A flag is thrown at the snap.  The ball is handed off to the RB for a twenty yard gain.

My question is when should the official blow the whistle?

This is a live ball foul. Play continues. After the down ends the defense has the option of the result of the play, or 5 yd. penalty from the previous spot and replay the down.

Now, if this is a case where a man in motion suddenly cuts sharply toward the line of scrimmage just prior to the snap, there is a school of thought that treats this as a false start, since what happens is essentially the man in motion starts the play before the ball is snapped. In that case, it’s a dead ball foul. Blow the whistle immediately and penalize 5 yds.