I'm going to give you an unscientific theory.

 

I have no stats and I'm sure plenty will scoff at this, but I believe defensive miscues so distract a player like say, Reynolds or Chris Davis, that it leads to MORE bad habiits and attempts to 'make good' at the plate.
Consequently, when a player is going well defensively, the confidence and self assuredness lends itself positvely at the plate. This game is so much a mental game that I'm willing to bet that in games where players fail defensively, they almost never do well at the plate. In a way, thats why Davis' "pitching miracle" in relief was such a welcome and rare respite from his 0-8 with 5 strikeout performance that day.Reynolds and Davis always have poor stretches of course. Both are strikeout machines. But I believe bad plate appearances are compounded by poor defense.
Anyway, it's just my theory.