I try to give players the benefit of doubt when it comes to injuries. My guess is that it's a nagging injury that's been affecting his performance all year and, like others have said, he finally decided enough is enough. The team doesn't need him to make a pennant drive because there won't be one, he's not going to be traded to a contender, and he wants to be as ready as possible for spring training, wherever that may be. And by the way, I think this could explain why he didn't slide on that close play at second base the other night.