Werth thrived in Philadelphia where he was surrounded by other good hitters in the lineup. That is happening for him in Washington this year.
Which is why he's overpaid at his price, but since it's not my money, hey, I love the guy. His triple-slash is about exactly what you'd expect from him outside of CB Park - his contract year .532 SLG was really an outlier. Except for that year, he's having his best triple-slash year ever.
And he does seem to have adjusted his approach - critics will point out his BABIP is an unsustainable .384, which is right, but I'm more interested in his % rates*. His BB% is actually slightly down from his career average, and his HR% is well down from his average, BUT his K% is way down - almost 8% less than his career average and his extra base hit% is up - it looks to me like the stats bear out what Davey and he says he's doing - taking fewer pitches and looking to drive base hits. Because of that he's making a LOT more in-play contact - that's resulting in good things (higher numbers of hits, higher BA, etc.) and a few not-so-good things (higher percentage of infield flies, lower percentage of HRs to FBs, etc.). Even if he reverted to his career average BABIP, it'd shave his BA down some, but he's still be very useful at the top of the lineup.
Overall, he's become a really good leadoff guy - sort of the prototypical "leadoff guy with power" as opposed to the "speedy, steal a base" leadoff guy. For my money, I'd rather have a smart baserunner smash a double in a gap than have a waterbug leg out a grounder and steal second. Same result, and doubles are cooler.
* - keep in mind he's only got 235 PAs because of the injury, so there's an SSS caveat to everything here.