Olajuwon and Duncan certainly have a positive impact on their teammates. Also it's how a Star player interacts with his teammates. Some guys really talk to their teammates and let them know what they need to do to succeed during a game. Some guys like KG set the tone for their team and get the other guys intensity up to the right level, cuz they know that level, whereas not all players recognize when they are letting off the gas.
It's not always about making others better, often it's making life easier for other players. Lebron is another guy that sets up his teammates and makes things easier for them. Some guys take the pressure off their teammates with how they perform and allow their teammates to only have to play to their strengths. Then you have players that actually hurt their teammates performance and that is where the idea of team killers or coach killers come from. Often they aren't players that lack talent, which would be easy to marginalize, but they are often players that have talent but don't know how to win or play within a team concept and their talent becomes disruptive rather than helpful.