I think it's interesting that Mark Cuban essentially just let him go. He had apparently committed to returning to the Mavs but changed his mind after DeAndre Jordan went back to the Clippers? He asked Cuban if he could go to Cleveland and Cuban essentially said "sure, whatevs?"
At least, that's how I'm reading the story.
http://dfw.cbslocal.com/2015/07/21/mavs-cuban-fair-to-let-jefferson-go-to-cavs/
Makes sense. Pretty sure he gave Wes Matthews the same deal.