I wouldn't say greatest mistake. Looking back at the 2008 draft, I think Stewart was the best RB tooken that year in the first round (McFadden, Steward, Felix Jones, Chris Johnson, Mendenhall). I do agree that NFL has changed were you dont need to be drafting RB's in the first round though.
Hindsight is always 20/20......
Actually, many folks were screaming when that pick came in.
That said, the same can be said about Luke.