And I guess Hasheem Thabeet was top 2 talent right

Kwame Brown
NBA scounts and GM's don't know everything. Dirk got traded to the Mavericks for Robert Traylor

Kobe got traded for Vladi Divac
MKG got drafted for the same reasons Anthony Davis did. They were both young and could still be refined. Upperclassmen in college are viewed as having peaked, which is dumb because Tim Duncan was a senior.
This logic is why the NBA is trash right now. Players make the jump because they feel they have to and don't bother to refine their games in college, even when they're not ready. You can't knock Poythress for saying if he felt he wasn't ready for NBA life and the pressures that go along with it. I think his biggest mistake was going to Kentucky. Each new freshman class took minutes away from him. He never really got a chance to develop his game playing for that school. If you go to Kentucky in this day and age, you should never stay more than 1 year because you will surely get overshadowed, which puts added pressure on a player to enter the draft even when they're not ready.