While he did have two 1st round RB's, they didn't always have big games, and when they didn't he threw the ball well enough to get victories(see, the Alabama game). Both backs were stopped cold and Campbell passed them to victory.
Two top 5 first round running backs.
When both backs were stopped cold... why did you think that happened? Because the defense was commiting all of it's resources to stop that beast of a running game. Don't you think that would make it quite easy for a QB to throw against?
If you know anything about football, the answer to that is yes.
That would make it easy for any QB to throw against. Apparently, a QB who was mediocre at best for his first 3 seasons could look okay in that situation.
If you think those two running backs didn't make it easy for Campbell to throw... you're delusional.