Fair question. Aside from injuries, it may come down to one of those do we need him to help get the sixth win against Indiana to become bowl eligible. I'm hoping we start 6-0 and a decision is made that we save him for next year. That said, I never get too concerned about playing freshman running backs because of the high probability that they may need a redshirt year at some point in their career.
If he's ready by NW, he needs to play this year.