Bay's always been a big swinger, so he strikes out a ton. Problem is that he also used to have a good eye and would work for a lot of walks. It's the latter-half of that skill set that has done the disappearing act this year.
Another interesting problem of his is in his LD%:
Look at that thing drop! He's either just not seeing the ball, or he's forcing himself to swing at stuff he shouldn't be swinging at. Either way, he's not himself right now. I think a change of scenery is what he needs, and the Pirates would be smart to trade him while he still has any trade value. That probably won't be this year, but it could be this off-season.