When Mendenhall is ready he'll get a chance to play, even if it's in a reserve role. He'll have fresh legs, assuming he's healthy after being on the PUP list, which will be key for the stretch run of the season. If Redman and Dwyer are hot though, Mendy's carries will be limited. There would be no reason to feature him when you have 2 guys working well together already.
Injuries always happen though so there's really no way to tell how much playing time he could get if healthy.