This happens often when players get their huge contract. MLB deals are all guaranteed. He worked his butt off to get where he is now and get that huge contract. Is he working as hard as he did before the deal? Who knows. Maybe it is just a bad first half, but you can't assume everyone wants to win a championship the same amount. Money is more important to some.
Once again, not accusing him of anything, but it wouldn't be the first time in history someone secured their bag and took it a little easy.