Walk on's who play well can earn scholarships, they have to come from somewhere. It's not unheard of for juniors and seniors who really have no option to leave to have their scholarships reduced 10-20%. When you see these big time schools bring in 15 freshmen every year you know many will lose their scholarships if they don't show good right away. In my son's case he was drafted his junior year and went right down to the deadline before deciding to return to school, His coach thought he was leaving and wasn't able to give him what he had been getting since he used most of it on other players, but he did get most of it. Makes it tough on the coach.