I know you asked gryph, but I also wanted to throw my 2 cents in.

I think washington overall is either awful to slightly below average defensively. Harper is about as average as they come defensively in right field, Eaton Is a below average cfer but an elite RF like Heyward on the cubs. However, If you take werth out of the lineup, play taylor in centre, move harper to left and Eaton to RF, you would be well above average defensively in the outfield, but you have dusty baker managing so that isn't happening... also taylor has a hard time hitting the ball lol.

Infield might be an unsolvable problem though. At 1st, Zimmerman is below average for sure as a converted 3rd basemen with a long list of injuries. At 2nd base Daniel Murphy is known to be one of the worst in the league. At ss, Turner is debatable. He is not known for his defense at the position and advanced metrics didn't like him last year, but a lot of scouts think he can stick at ss. And finally, Rendon is probably you're only saving grace defensively if he stays healthy. Rendon is not necessarily known for his defense, but advanced metrics liked him last year at 3b, it's his natural position (I think) and last year was the first time he's had a really healthy year.

As for wieters, he's pretty average, but he isn't the best pitch framer.

Overall, you're definitely bottom ten defensively, with potential to be top 15 if taylor replaces Werth. Luckily that nats pitching staff is so good, and the bats are really really good if Harper can get back to being a stud.