This is the first tracking of WAR for the Nationals this year that also takes into account defense. It looks like Fangraphs waited for 2 weeks before first posting defensive numbers as a component of WAR. Obviously, the defensive numbers utilize a small sample size, but as a component of WAR, they count. Some players known for their defense (Span, Espi) are calculated at negative right now. This will most likely get sorted out as the season goes on and the sample size gets larger.
The best week goes to the Nats youngest players Anthony Rendon and Bryce Harper. Rendon doubles up his first week and Bryce dug out of his 1st week hole. Desmond, on the other hand, with a team worst defense score and a negative batting rating is only bailed out by his position (SS) adjustment.