Motivations vary in the NBA, but some quality players end up performing well so they can be traded to a different situation. Of course they still want to help their teams win, but in the back of their minds, they're hoping for a phone call from the general manager.
It happens every year, and going into the 2013-14 campaign, there are six players who have emerged as auditioning stars. And do note that we're being pretty liberal with the definition of "star," including both household names and players who have no choice but to function as a "star" on their own squad.
These featured players just aren't in the right situations.
Some of them aren't part of the long-term plans and need to find a new role. Others just know they might be moved and want to impress the league's best teams. Others still are stuck in roles they don't deserve and need to find a more promising landing spot.
Regardless, they're all auditioning.