The only reason players don't pan out is because of bad player development programs with in the Team, the player lacks motivation, or the player is just a knucklehead.
Marcus Williams, Univ. of Arizona...great work ethic, not a "knucklehead" by any means, drafted by the Spurs and, a year after he was traded, signed back to the Spurs, who are excellent with player development (one of the best franchises in the league when it comes to that).
How about James Anderson? Those two kids are just two I'm pulling out of nowhere, because they were drafted by San Antonio, and both are very hard workers.
I'll go a step further, and note players that I personally know. Wayne Simien. Cole Aldrich. Darnell Jackson. Julian Wright. Wayne was one of my friends, just as Kirk Hinrich and Nick Collison were, and he didn't pan out because he had a bad attitude, or wasn't a hard worker, or Miami's player development was terrible?
Instead of you doing it, I will. Some players just aren't cut out for the NBA. Some just can't get it done. You can't open up a book of draftees and choose five or six guys, out of the first round, to stick on our roster, all based on what they did back in college, and think that it will translate to the league.
If it was that easy, there would be no such thing as player scouts (who are paid generously). A scout's job is to analyze a player's game, over a course of 10+ games, and determine if he has the necessary skills to become a pro athlete...even if it's someone like Kyrie Irving, who played 11 games total in college before landing the #1 pick.
Real talk, there's more to it than what you say.