Huff could be more solid in a better system on a better team. Maybe even if its just situational.
Russell, I think, still needs a lot of work and has had the unfortunate luck of being stuck on a terrible team with a revolving door for coaches. Case in point, Alex Smith. Different offense and coaches every season, nobody can play consistently under those circumstances. But I also cite the case of Randy Moss. A guy that didnt care at all when he was on the Raiders. He gets moved and suddenly has NFL records under his belt.
Heyward-Bey is.. a 4th slot WR on his best days, should've been a later rounder.
McFadden, I dont know about. Most average running backs could do good behind a great offensive line, which he doesn't have. I think he has the physical skill set to be a good asset in a 2-back system but again, the Raiders don't have much offensively to support anything.
Gallery is okay. He's another guy with good natural ability but he's part of a struggling offensive line on a terrible team. I have no doubt that he'd step up his game elsewhere.
I could be wrong about all of these, but I'm also a firm believer in the philosophy that most talented college players can play well in the NFL if they are brought up in the right system under the right coaches.