Aren't scholarships given on a year by year basis? So when you sign with a school, you aren't guaranteed 4 years, if the school wants to revoke the scholarship. Not something a school wants to do often, as players might not want to commit if there is a history of the scholarship getting taken away at a later date. I think this is what happened when Calipari was hired at Kentucky, many of the players did not have their scholarships renewed.