I'm not sure he would be that good as the main back. He was as effective last season as he was because it was something different and surprising.
He's a bit too small to run between the tackles. That could be really problematic. In a role like Sproles for the Saints or as a change a pace back Cobb good be really good though.
Lead back i think he could get maybe around 900 or so. Hard to say. I think his runs would look something like 1, 3, 2, 4, 6, 25, 8, 1, 3, 30 ect. I don't think he would have a great YPC but he would break off a couple of long runs, where the majority of his yards would come from. The thing i do like about him is that he would be one of those backs who would be hard to find when he is running behind his blockers.
I don't think he would make a very good lead back. He needs to be in space, outside the tackles. You can't sustain z run game if you don't have the threat of running inside. I think he would be below average and like Cheese said, would probably break the occasional long run. I'd say he'd hit around 700 yds and an YPC in the low 3's. not that I'm knocking on him, love him as a slot receiver
Just how I feel. I agree he'd be used in stretch plays and draws etc. but when that's all you've got, how's it going to work out? That's all Green was good for too, and although Cobb is more elusive than Green, I think it's been shown you can't be successful when that's your bread and butter. I think you need someone who can gain on the tough interior runs and I don't think Cobb could do it. There is too much speed in today's NFL to make a living on that.