He looks very sad, but perhaps he's just thoughtful. Mick is undeniably an anxious dog at times, and his crate is his refuge where he feels safe.
He's the first dog we've ever had who was crate-trained when he came to us, and maybe that's what the phrase means (we've had other dogs who accepted the crate for travel, but never one who preferred it). Our other dogs preferred to spend most of their time sleeping somewhere in a room where we were. Mick goes to his crate instead.
When there's food or action, or beisbol (e.g. on our laps while we watch tv) he shows all the doggy signs of happiness and contentment. So I think this is just an old habit.