If he's so good why do clubs keep moving him on? You usually want to keep your best talent....
You´re wrong there. He doesn´t get moved by clubs. He just moves on all by himself. That´s a big difference.
The reason he decided to move out from Barca was that the coach publicly showed him that everyone in the team needed to adapt to his set of rules. All but Messi, who is the golden boy.
As Zlatan is somewhat like a diva himself, and is used to be in the centre of the action, he just couldn´t cope with that kind of treatment.
He started his career in Malmo FF, Sweden (1994), then moved on to Ajax (2001). After that he signed for Juventus (2004). Because of the big Serie A scandal in 2006 he went to Inter. In 2009 he was traded by Barca, and in august 2010 he went to Milan.
Where in that row of transfers was he traded against his own wishes?