It's good that Twinkie didn't change his approach there. The Nats shifted away from his tendency to pull, and pitched him to the outside. Trying to aim for the opening -- even though it's actually where he hits it most of the time -- wouldn't have been a swell idea on an outside pitch. Of course, the Nats played directly into his willingness to flick it the other way to the boxes for the short tater, which was probably a foolish risk on their part.
But no, I don't think the Nats were playing mind games at all. I think they were just trying to steer him out towards the big part of the park, and put the fielders where they hoped it would go. It pretty much worked out that way, since he hit it close to where RF had been shifted (RCF), but it was smoked on a line. A grounder or fly there has the desired effect for the Nats, but he's just hitting it too well right now.