i don't know how it works in the NFL, but i can tell you an actual experience that i had while working as one of the video interns in the athletic department at a school in the SEC.
while working on the annual "stroke-me" recruiting video to show the media on signing day of all thetalent we had recruited, we stumbled across a tape by mistake of a guy from south Texas. it was UNREAL!!! he was a kicker/cornerback (weird combo, huh?) but the guy was incredible. aside from a tremendous leg (the highlights included a 53-yard field goal and numerous kickoffs out of the endzone. that's right, OUT OF THE ENDZONE!), what really stood out was his tremendous playmaking ability on defense.
the first play showed him forcing the quarterback on an option play to his side of the field. he forced the qb, then amazingly changed direction, caught the pitch, and took it the distance for a touchdown! the rest of the highlight tape had numerous other plays showcasing his incredible cover skills, speed, and general phenomenal athletic ability.
long story short, i took the tape to one of the coaches, a young black guy who we all thought was much cooler than the white head coach (who is known as a black guy trapped in a white man's body). we sat down in his office, where he zoomed past the kicking portion despite our need for a good kicker. when we got to the defensive highlights, the first words out of his mouth were, "Wow. Nice play." that was quickly followed by three repetitions of the same phrase.
at this point the coach turned to me and said that this is the point in the process where the coaches need to go look at the guy in person, to make sure the guy is as impressive as he looks on film. he might be in a small conference, so it's hard to see exactly how fast, big, etc. the guy is. i said okay, the guy plays in the top level of Texas high school football, so that looks good for us right?
the coach replied yeah, this guy looks like a player. then, no kidding, this is what happened...he said, "Now we need to schedule...(hetooka long pause as if he just noticed something), is he a white kid?" i responded, "Yeah, or he's an awfully light-skinned brother." "Well tell him we'd be more than happy for him to walk on, but we don't have any scholarships available right now."
and that was that. and that came from the youngest, coolest guy on the staff who coached linebackers and had several white guys that he bragged about at the position. i would say it was unbelievable, but i was there and saw it first-hand. that'sthe kind of attitudethese young white skill-position players have to overcome, at least in the SEC.