Let's not get carried away here. The Nats still have holes to fill, most obviously with the bench and bullpen. If I were GM and I wanted to hedge my bets for postseason contention, I would sign a bat somewhere. The "upgrades" I see out there are Cano, Ellsbury, Choo, Beltran, Napoli and Kemp. Kemp is a hard sell given the injury history the past two seasons and obviously the Dodgers aren't going to just give him away. Even without one of those guys, the Nats probably have an above average offense and one of the top three rotations.
I'd sign Boone Logan, promote Solis to the pen, eat half of Soriano's yearly salary (4.5 Million) and trade him to the Orioles for a prospect, sign Eric O'Flaherty and go with the following bullpen: Logan (L), Solis (L), O'Flaherty (L), Stammen (R), Ohlendorf (R), Storen (R), Clippard (R). Clippard is the closer and if Ohlendorf falters even a bit, Roark is brought up as a replacement. Leave guys like Matheus and Garcia in AAA to either bounce back or complete rehabbing and use them as insurance if someone underperforms or gets hurt.
Bench should be Moore, Hairston, Espinosa/Walters, Brown and sign Yorvit Torrealba as the backup catcher.