Tuco is right. Elite dudes are often put on a "three year" plan; I read this when we were hot on Lewis. Basically, college coaches straight up say, "Hey, come here and kick *** for three years, then declare for the draft, no harm no foul." With this kind of talent, that's just how it works. To add to what Tuco is saying, I think SOMETIMES elite dudes stick around for a fourth year if: A.) that specific year's draft is rich in their position, so they come back for a fourth year to improve their draft stock next cycle, or B.) they just happen to personally value a degree. Both are exceptions, not the rule.