What he said, plus these are different times; with year round workouts athletes are more ready physically today then when I played, but the nature of high school doesn't prepare them mentally for Big Time programs. That's why its great when you get a kid graduate early and come in at the half year.
The great athletes from any generation usually have been freaks since they put on cleats, and probably could out athlete 90% of the people they played against.
Then college happens - and now the playing field is more leveled out. College sets everything up to compete - off season workouts too. Competition becomes a different mind set - you're not competing against a common enemy, you're competing with your teammates.
Some very good ones don't make that transition very well - sometimes guys that came in with a chip on their shoulder; something to prove, surprise people. But no longer being the big fish in a small pond, can manifest itself into lack of effort. They act like they don't care and rationalize its the coaching, they're not using me right, its the QB, its the scheme, its blah, blah, blah...
When you arrive at college, you've heard it all, but you need to see it. You need to see structured leadership, where veterans take you under their wing when you've done something right (Why I love the group leader aspect Manny brought) to facilitate the buy-in. And you need to see program movement and results, or if there hasn't been much lately, then you need to buy into the Tradition and see the pathway (TNM). I know how I approached it, I didn't play D-1, but a chip on my shoulder served me well and I was a four - year starter.