He would have had a really good line protecting him in 2013, since Golson was off the team.
I know he did decently in Cincy, but that line wasn't exactly that good, and he was getting hammered left and right every time he dropped back to pass. It's not surprising that he got hooked on painkillers during his time there.
Had he stayed at ND, who knows? Maybe he doesn't develop a pill habit, and becomes the QB we all thought he could be.