I think the success of the QB will have a ton to do with how good the running game is. Blum doesn't read defenses well, but he can throw the ball a mile. Blum will also complete only 50% of his passes, but the deep ball will open things up a bit. When he throws the ball deep, I think he tosses it as good as anyone in the BSC. If he learns the game and becomes more accurate, I think he can be serviceable.
Hill on the other hand, knows where to go but lacks some zip. He also cannot throw the ball as deep as Blum and has a tendency to try to force things that aren't always there. Hill needs a good running game to be successful, so the defense is forced to honor the play action. Hill will complete passes at a higher rate, but he tends to check down and cannot throw the medium and long out routes. I think that Hill is every bit as good as Blum at this point.
I feel bad for both of these QB's. Hill did the best that he could and he did not have a running game and had to play from way behind most of the time. Now, this year, Blum will be the one that shoulders the blame for the losses and at some point I expect ISU will turn to Hill to get the team on track. If the defense plays better the offense and the QB's will look better. I think the defense will be better this year, but I doubt that they will hold opponents under 40 points a game. The running game will be abandoned and both QB's will appear to be worse than they are.
ISU simply needs to run the ball as much as they pass and control TOP.
That is my two cents.