I don't feel like trying to explain to you the play type they were running. After establishing a run game its a sort of option play that allows the quarterback to disect the defense once up to the line and then decide. go watch the replay. The run game is the base and the receiver still runs a slant route. If the QB decides that the d is playing the run he has the option to hit the receiver on a slant route instead of running the run play. the line will still run it as a standard running game. go back and watch and you will see well I saw at least 2 if not more linemen down feild because they were running it as the base play. It's nobodies fault, just a shitty set of circumstances.

edit: we had a similar play in high school. the receiver always ran the pass route looking. The back only knew what the play was gonna be based on how the quarterback stepped back....left foot take away was a fake hand off to pass...right foot take away was a continuation on the run game.