The Nats can't beat playoff teams. 4-18 vs Braves, Dodgers, and Cardinals. They did go 4-3 vs the Reds (real early in the season) and stand at 2-1 vs the Dbacks so far but all the other non-losing records are vs losing teams.
The Nats are seemingly noticeably better than the bad but noticeably worse than the good. That sets them up to finish exactly where they feel most likely to, a few games out of the playoffs. It's something to take account into planning for next year. It's not just about getting better its about enough getting better than the good teams to make a difference