I think it's important to look at yards per attempt for each player. It's easy to have high completion rates when you are dinking and dunking.
Todd Boeckman 7.67
J.T. Barrett 7.60
Troy Smith 8.54
Cardale Jones 8.60
Braxton Miller 7.94
Boeckman and Barrett are big time dinker and dunkers, whereas Troy Smith and Cardale Jones were much more likely to hurt you deeper.
For comparison's sake, Andrew Luck at Stanford was at 67% and 8.9 yards per attempt for his career - incredible. His sophomore season he was a 70% and 9.0! Deshaun Watson is at 67.6% and 8.5 for his career.