Its common but when it comes to a tweet that says he lack the desire to win then that create alot of speculation. Positive speculation would be that he feel uncomfortable with his teammates therefore he doesnt have that drive to win the games. It happened when you play alongside people that you hate but in this case I totally speculate that it could be 322 scenario
I know that feeling when you lose the drive to win a game. That sucks on the teammates end and they're already down and someone don't want to play competitively even if they can still win a tough game.
Anyway this is not really the first case for Parker, a year or two ago he had issue with his teammates as well.
I can't remember that he's got some past issues as well.
So, if this is the second or third time that he's got into this issue. The real issue is on him, his attitude and despite he's a good carry, most teams and teammates are valuing more attitude and good chemistry.