bandwagon athlete 

An athlete whose team is liked only because he plays on it. They are liked by fans wherever they go. These fans only like the player, not the team. (i.e. somebody turned into a Miami Heat fan when LeBron left Clevelend and hated the Cavaliers, but then was a Clevelend fan once again when LeBron returned).

LeBron is a bandwagon athlete.

bandwagon athlete by The Truth_01 April 28, 2016