The Phillies and Braves might explode in the last third of the season, but even so, the Nats have to aim for at least 88-90 wins. Say 89 to split the difference, they need to go 40-23 from now on.
I don't see that happening at all. I expect the Braves and Phillies to finish at least a game or two above .500, so even with reduced expections, the Nats need to go 37-26. It's doable, if they play like May, but if they play like spring training, April, June and July, they obviously have no shot.