I think there should be more features to determine a player's rating like leadership ability and confidence level (bad games bring it down during the course of the season and good games give it a boost) which should affect how he plays and makes his team better. Also, they should add something to determine how a player performs in critical situations at the end of the game.
In NBA Live 2005, I've also noticed that if you sim a game, a lot of the time your star player can't even get 10 points due to lesser shots taken. In NBA Live 2006, they should have something that makes teams look more to their star players for offensive production.