Well, that's a bit disappointing Bogut chose Cleveland over Boston, but not terribly surprising. I think Bogut, more than anything, wants a chance to stick it to his old team. He clearly wasn't happy with being traded, even if he understood why it had to happen.
But if winning a ring as a guy who is unlikely to get much meaningful playing time in Cleveland is what drives Bogut, good for him. I'm guessing he could have had a bigger role with Boston, but obviously that wasn't his biggest priority.