There's no reason a 6'8" shooter didn't, over the course of 4 years, learn how to create his own shot. If Huggins was Cartier's coach for 4 years, he would have been drafted.
Another example is Shawn Rhodes. Dude was 6'10" and couldn't play with his back to the basket.
You don't just coach to a player's strengths, you're supposed to make them a more complete player.