Some of it might boil down to taking those All Americans and fitting them into an actual team. I'm sure this isn't true of all of them, but I think most of those types of players are used to being THE man on the team. Everything runs through them, they are the absolute best player on the floor most of the time. Suddenly they have coaches that may make them work, may not let them play 40 minutes a game. Or they simply aren't used to being a team player and it takes a learning curve to try to take 3-4-5 of these types of guys together and make them mold themselves into a team - sometimes it works, sometimes it doesn't. Sometimes the kids don't pan out to be 5 start talent at the next level. Some may very well just be playing for themselves and the NBA next year. Again, these are general assumptions. And certainly there is talent there, but it doesn't always work to form what is essentially all start caliber high school teams at the college level. The raw talent can usually get them some success, but it's not guaranteed, especially in the tournament.