I agree with this. The concern with McGahee when he got here was his durability. He's having a great season and got more touches already than he's had in a season since 2007, but he's doing it with a plate in his hand, a wonky hamstring etc. He's 30 now, which tends to be the best before date for RBs.
We'll definitely be needing to add a back at some point in the draft. I generally don't like taking a RB in RD1 unless their speed/size/power combination is elite, but if Trent Richardson is available in the late teens, early 20s, he's likely to be the BPA. I'm hoping we end up with a CB with our first pick, but it would be hard to complain if things shook out this way.