Sometimes I'm not so certain that white announcers and sports casters in the media have bought into the caste system per se, in that they believe white athletes are not as good as black ones, but more that they don't want to be perceived as 'racist.' So, they refrain from making any kind of what might be considered controversial remark about a white player who's success hasn't already been 'determined.'
For example, if a white announcer labels Jurevicius as a #1, since he isn't already 'established' as a number one receiver, some one behind the scenes might remark that he is making said comment merely to boost JJ because he IS white. Yes, I know, black athletes do the same thing all the time - the hype around M.V. more than evidences that fact. But blacks are still given a pass when it comes to that type of commentary, whereas whites are not.
I think perhaps it is a combination of both accession to the myth of black athletic superiority and fear of being labeled a 'racist,' which keeps the white media from acclaiming white athletes the way they deserve.