I just dropped him after holding him all season - I'm finally getting some depth at RB through WW activity.
After watching him in a few games, his lack of fantasy productivity IMO is driven by a few things:
1) The Lions are generally bad running the ball. No matter who's running, you don't go 4 years w/o a 100 yard rusher if you're decent at running the ball.
2) The Lions use different RB's in different situations (Riddick on 3rd, Washington near the GL, and Abdullah most of the other times).
3) Abdullah isn't a home-run threat - if he doesn't break a long run, he'll usually cede GL carries to Washington
For me, this was the combination that led me to drop him. Any 2 of the above 3 and maybe he makes sense to hold, but the combination of the 3 basically means, IMO, the ceiling for Abdullah is ~75 yards on a typical week...and that's being generous. He's just not a high-upside type guy, nor is he especially consistent. Risk with no reward. No thanks.