The Pythagorean Expectation calculation can be used to estimate over/underachievement based on winning percentage vs. expected winning percentage given runs scored.

NL East contenders to date:

Nats, actual .534/expected .542/difference -.008 (1 more win)

Braves .583/.550/+.033 (5 more losses)

Mets .517/.511/+.006 (1 more loss)

Phils .508/.471/+.037 (4 more losses)

By this calculation, Nats should be expected to trail the Braves by just 1 game and lead the Mets by 4 and the Phils by 8.

One can interpret this to mean the Nats are the only underachievers among NL East contenders.

https://captaincalculator.com/sports/baseball/pythagorean-expectation-calculator/