Athletes go to college to get notice by national associations like the NBA or NFL, sure it's sounds stupid to go to college to get in the NBA, but it's the only way to get notice theses days. The NBA or NFL need people who are smart to know good plays or just make good decisions.
I am a cyclist, and while it takes up much of my time, I am able to keep by grades up fairly well, at least a B+. However, I do go to a fairly prestigious high school, and would consider myself among the more scholarly class of high-school students in this nation. I will say, it's difficult. The time and dedication, the stress and lack of sleep, all these make it challenging. For some students, athletics is their outlet, it sure is mine, it relieves stress, helps them if they have problems at home, at gives them other opportunities to exceed than in school.
Athletes have it hard we have to maintain our energy for games and practice, school and our social life. That's just a lot more stress out into us. Our grades are what got us on the team, well no not technically we got ourselves on the team, and of course the coaches. And well, we should just maintain the grade we had when we got on the team.