I can't understand the logic of sending Moore to Syracuse so the Nats can keep both Nady and Moore in the organization. As best I remember, the point of a baseball game is to win by scoring more runs. A team does that by using its best players. Moore hits better than Nady, so Moore is better. (And he looks like an adequate LF and a decent fielding 1B).
...and I don't see evidence that DeRosa is a better 3B than Lombo, or better LF.
DFA Nady and DeRosa. Bring up Corey Brown, who was hitting .295 with 16HR last I looked at Syracuse.