The most intriguing position battle has little to do with actual playing time, but more an allocation of snaps and touches between Lions RBs Reggie Bush and Joique Bell. Both figure to receive a lot of touches as new offensive coordinator Joe Lombardi will likely use many backs in a bunch of different roles. Bell may actually receive more carries as a straight runner and could be more valuable in goal-line situations. Bush is going to be a piece used out of the backfield and also out wide so his receptions could skyrocket.
This is also how we see the touches shaking out. We currently project Bell for 235 touches (192 carries, 43 receptions) and Bush for 206 (145 carries, 61 receptions) so Bush has a bit more value in PPR formats, while Bell has the edge in standard. The redzone touches will likely swing the value between the two backs. Bush out-touched Bell 37 to 29 inside the opponent's 20-yard line last season.