I believe he was moved to RB his Freshman year ('12) right before Pachall's incident, and was moved back to QB the Friday before the Iowa State game, and was the QB the rest of the season. When Pachall came back to be the starter the following year ('13), he was moved to WR because he was too athletic to keep off of the field. When Pachall broke his wrist, Boykin became the starting QB again.
Timeline may be a little fuzzy, but that's what happened. It was split about 50/50 on who thought he would make a good college QB, so I wouldn't say no one here or on staff believed he would never be a QB.
Boykins success was due to the installation of a system that highlighted his strengths, not Cumbie. If Cumbie was such a great QB guru, why all of the bad QB play after Boykin? Don't bring Hill into this. Again, Dykes came in and built the offense around what Hill did best.