In college, I think you better have a qb with the ability to run, avoid the sack and make a critical first down with his legs. If that guy is also tall, then that is even better. In the pro's, trying to run might just put you on the disabled list.
I always thought that Peyton and Tee were good examples of this. Peyton was great, but he couldn't quite get us over the hump in college. In the NFL, he could. On the other hand, Tee lead us to the national title, but he did not succeed in the NFL.
The difference being, Tee had the ability to make that critical running play when we needed it. Except for one play that surprised everyone in the stadium, I don't think Peyton did a whole lot with his legs.
That may be an over-simplification, but that is always how I saw it.