from doc's all 22 link
“We knew he could throw the ball. Him in that shotgun-type of look, where he looks like he’s going to hand it off, sometimes that slows the rush down because [you don’t know] if it could be a run, or it could be a pass. Once we know it is a pass, we can go after him.”
and this is why you keep a back in at this level. you have to at least threaten the run, even if running doesnt work. you also have to keep the back in for blitz pickup to prevent a free rusher. this becomes infinitely more important when you have a young quarterback who's not as able to protect himself with hot reads and only a week to prepare.