The Steelers will probably have two RBs ahead of your rookie. Blount was with the patriots last year, he'll be mid to high 80s after his playoffs. LeVeon Bell will be high 70s, and archer will be their change of pace, because he was the fastest player on this draft.
Trent Richardson will be 2nd on their depth chart behind Brown who had an ok season, will probably be low 80s.
You're talking about madden, they're not just going to release Crhis Johnson, he does have a two year.contract, but you won't get on the field before then.
Reggie Bush hasn't had a good rushing season in many years, you may be able to outplay him.