As we see it today, Bell will be the RB for the 2018 season.
Now, what sense does it make to use your first round pick on a guy that won't even see the field more than a hand full of snaps all season? We have a legitimate shot at an ILB that can become what Watt is but on the inside. OR, a DL to compliment an already stellar group, OR an edge rusher that actually puts QBs on their ass. Why would you select a backup RB, at best, at 28?
Now, think about RBs in the 3rd round and beyond. Bo Scarbrough has a very similar spider graph as AP, and can be gotten in the 3rd by most analysts. Ronald Jones(sub 4.4/40) has become a 2nd-3rd rounder because he needs to add weight. Going by the mocks and sims, Penny could be had in the 5th.
A RB in the 1st does not make sense for this team.