Jumbled mess from a fantasy perspective (if that's where you're going with the question).  How I see it:
- Mike Gillislee will be the "#2" RB and is the most likely direct fill-in for McCoy (ie he has a similar playstyle and they can call the same types of plays/schemes with Gillislee in the game that they can with McCoy).  Minimal fantasy impact absent a McCoy injury but could be a handcuff option.
- Reggie Bush will be a gadget player.  I expect them to line him up at WR, in the slot, pre-snap motions, etc.  May also return kicks/punts.  I wouldn't expect too much from a fantasy perspective outside of an occasional big play.  Far too inconsistent to really start him barring a McCoy injury.
- Jonathan WIlliams is the closest thing they have to Karlos WIlliams from last year.  Could vulture some TDs and be a change-of-pace back as he plays bigger and runs differently than the other 3.  I wouldn't expect anything quite like what Karlos did last year.
Reggie Bush is currently the #2 on the depth chart, with Gillislee #3 and Williams #4, for whatever that's worth.