Remember when McNabb accused TO of being racist because he said Brett Favre would have done better than McNabb in the Superbowl? That slightly tarnishes a lot of what McNabb has to say now for me, especially on the subject of race. Evidently it was Brett Favre's never missing a game in his entire career which was the salient point. Whether McNabb really thought TO was being racist or wanted to strike back at him in some manner, it made me think less of McNabb and his opinions.
That all written, I don't doubt there's still a bit of that outdated old (wrong) cliche about black QBs still floating about. I would like to think modern coaching staff wouldn't be dumb enough to let themselves fall into such preconceptions about people but wouldn't be overly surprised if some within the organisations are rather outdated in their thoughts, even if experience has proven them to be incorrect.
I wonder if the same happens the other way round for RBs? I can't think of a team with a starting ball carrying RB who is white. Peyton Hillis was probably as close as it got last season and that was only because everybody else was injured. Do you think people now have the preconception that white guys can't play RB?