The Washington Nationals simply do not have offensive firepower. Individually, the players are performing around their career averages. So we can rule out clutch hitting as an offensive woe.
Last year the Nats left the 12th most runners on base. This season, 28th. But this year the Nats simply have nobody to leave on base.
The Nats lack in all 3 major offensive categories: AVG, OBP, OPS.
In 2012 the Nats had the 8th highest team AVG - this season, 27th.
In 2012 the Nats had the 12th highest team OBP - this season, 28th.
In 2012 the Nats tied for the 7th highest team OPS with Detroit, DETROIT! - this season, 25th.
Luck is not to blame. It's just the lack of offensive talent. It's time to make a move or two, or three.