OR.. maybe.. the Coach said something like,, the play is designed to go behind the Guard,, now go behind the guard or I will find someone who will!
Some of you act like football is purely black and white. Its not. There are many variables to the game. Many of which none of us fans are privy to. We don't know what the coach has told a player. We don't know what the coach has game planned, and how not running to your assignment might effect that plan. Maybe the coach don't want his RB to cut back until he is on the second level because that effects how a misdirection play will be used later. Maybe the coachs want to get a feel of how the LB are reacting to a certain run to see where the passing lane is at for later.. which can't be determined if the RB don't run the proper play.