Moving a player too soon into the next level can kill budding talent. JR Smith is a prime example. He should have never went pro, should have gone to Duke as he planned, where Coach K's philosophies and firm teachings could have made him a great player, at least a decent one. Instead, he had a terrific McDonald's game and took the leap. He's struggled against superior talent and has floundered trying to become an adult.
Different situation in some ways with Mahinmi, but the past decade is riddled with young players who have broken in half trying to get into the pros too soon. He comes over too early, he may not develop a post game and only be a shot blocker. Who knows?