Each back seems to have some different qualities.
the question is this: will the Gophers adjust/tweak their game plan to account for the different skills of the RB's? If they come out and try to pound inside zone all game with Wiley and Potts, that might get you by against Bowling Green, but I don't think that works against IA or WI.
I hope they use the non-conf games to experiment a little bit with different sets, different personnel groups and different plays.
Bottom line, if a RB is better at running outside, then don't have him running up the gut. Put players in a position where they have a higher chance of success (and a lower risk of failure....).