Lets cut thru the bullshit.....the vast majority, not all, of black QB's don't translate to the NFL because they rely way too much on pure athletic ability in college instead of reading defenses properly, etc.... and there are white examples too....namely Heath Shuler. the guy was a fantastic natural athlete in college and it carried him to the NFL, but he was "too dumb" to learn the playbook and analyze NFL defenses at a fast enough pace...so his career was a bust.
There have been plenty enough black QB's to make a comparison, and the only ones with sustained success play the position "white" for lack of a better term. They read the defense and make the proper throw instead of tucking the ball and running everytime their primary receiver is covered. That works in college where they are vastly superior athtletically to 80% of the guys on defense, but not in the NFL where most defensive players are on the same level athletically. Vick never learned it, and was a marginal NFL QB at best, with a highlight reel run every 3 or 4 games that would be played to death on ESPN.
