Not sure about Oakland's plans, but just guessing that J.Russell will be the starting QB so they'd like to keep a vet RB around and work in M.Bush so still expect to see somewhat of a RBBC in Oakland.
I don't think JaMarcus or Bush will get playing time as long as a. they are mathematically alive for playoff contention - don't laugh too hard, they've looked A LOT more competitive than anyone thought they would through four gamesb. the starters at these positions (McCown/Culp and Jordan/Henry) are available and healthy. Rhodes is going to be a COP and 3rd down RB, not a starter IMO.To whoever mentioned Griffith, he is the fullback, not a tailback. However in this offense the fullback does get receptions and short yardage trick play type runs.