if you can get an adrian petersen/darren mcfadden/ladanian tomlinson of that caliber you take them, they are game changers but you also may get lucky in the later rounds. of course a good running back is nothing without a goof offensive line
Of the 32 NFL teams, 27 have first-day picks manning the starting role (29 if you count Cadillac and Brown, who are injured) There are only four undrafted RB's at the top of the depth charts, while 21 teams utilize a former first-round pick. Sure, you can find some late-round gems, but the bottom line is, if you want a starting RB, you better be willing to at least spend a first-day pick on him.
It'd be nice if someone picked up Troy Davis.
If you have a first round pick and need a running back ou have to go with Darren Mcfadden its just that simple, too much gamebreaking potential to pass it up. Why wouldnt you take the best player in the draft, who has a ton of potential? It just would not make sense not to take him.