The best usually bring some up to or close to their level of play
LeBron is one of the most dominant players ever. But he is not one of the best teammates ever. With LBJ on your team chemistry suffers, young player development is in hold. He sucks the air out of the room and off of the court.
Oh, plus he is a flopper, a crybaby, and displays a huge sense of entitlement when it comes to hoops.