Two new items would help, IMHO, to make superstars on AI teams behave like superstars.
#1: Add a role (starter, bench warmer, etc.) of Superstar. Then teams could designate one or more key players who are the guys who they depend on for scoring.
#2: Add a slider "Find Superstar on O" The higher the slider is set, the more often they look to get the ball to the superstar or run plays that feature the superstar. When this slider is at 100 they would pass the ball to the superstar every time. At 50 they'd run the normal offense. For example with the Cavs LeBron would get the ball every time. When he passed to someone they'd either take a shot or pass it back to him. At lower (between 50 and 100) the superstar would be featured less.
Even with the right playbooks, right now 2K9 does not get the ball to the superstars enough. Guys like Tim Duncan don't get it enough. In 10 played AI v AI games Lakers vs Cav neither Kobe or LeBron ever scored more than 20 points.