I do agree this seems to be a decent sized failure in my opinion. Especially when, I think, they had a good understanding of the extent of Edwards injury by the time the draft came around.
I can't say that there were a plethora of great RBs in middle rounds of the draft, because this felt like a weaker draft for RBs than usual, but when you know Edwards recovery is going to be a long one, and Dobbins just had a significant injury, I think you need to do more than add a 6th round RB (who ultimately didn't make the team basically). We should have known you can't depend on FA, even if somebody like Drake or Davis are upgrades.