The argument I've seen is that if a teacher doesn't pass them then they wont get to showcase their skills and it will ruin the only chance the have of making money - going pro (weak argument as very few go pro). The real reason is the huge amount of $$$ associated with college sports. If a professor fails a key athlete and he can't play that means real $$$ out the door for the college (TV cash, ticket sales, and alumni donations).
Besides straight out cheating (answers before exam) and tutors who do their assignments, I've heard of some getting to take exams on the road with them when travelling for games.
Of course, all my knowledge is based on TV too (albeit HBO Sports, not a made-for-TV afternoon special)
