re: Bama RBs in the NFL

I think there are a number of factors that have already been brought up. One, Bama normally out-talents everyone they play in college, which means less gametime against equal competition vs the NFL. Trent has great physical tools, but I always felt he lacked true physicality between the tackles like Lacy does. He tended to have lackluster games against great defenses because he tried to bounce everything outside when there was nothing there instead of putting his head down and getting what he could. Worked against most teams because of talent, but not against the LSU's and not in the NFL.
Two, most teams in the NFL just don't emphasize the running game anymore. They aren't looking for the best pulling guards; they want great pass blocking tackles. So in some ways, Bama may actually have better run blocking O-linemen than some of the teams their running backs go to. RB's are expendable in the NFL because those guys are expected to run through a brick wall every time and "move the chains". The rest of the time they pass protect for the QB so he can make the big plays. If a guy like Richardson or Peterson went to a team like the Seahawks or Texans (who draft undrafted free agents and turn them into 1000 yd rushers) that actually base their offense on the run and draft the guys up front to do it, they would be all-stars.
On a related note, I think the guy who compared Saban's coaching to Leach a vaild point, but not on the offensive side of the ball.