I like the premise of a 50+ minimum and a 65+ potential (60 would be enough). There are two alternative reasons to have a 'crappy' QB though
1. A Kick Holder - only on the roster to hold kicks and play at QB on the rare occasion a starter is injured.
2. Has the attributes to play in a different position (Taysom Hill) where he can play RB/FB/TE and again would merely be an emergency option if the starter is injured.