You should appreciate him for what he did which is to give you guys a world series. Look at the offense without him, not very good. If damon went from the yankees to the red sox after helping us win a world series, I would cheer him still initally. He comes up to the batters box and gets a hit and steals a base on the other hand, then I would boo him.
What I'm saying is cheer him when he's announced, let him have it when he's announced to start the game. It might seem like splitting hairs, but it's actually very different.