You have to remember, they are playing pretty much under the same conditions they would be if had a shortened bench. As it stands right now, once the All Star break is over and things get going again next Thursday in Milwaukee, for the first time is a long while, everyone will be there.
If you look at who will be available, and you include Zach Day, the Nats will have 27 healthy players who are all worthy (well everyone except Willie or Wontie Cordero) of a roster spot. With those number, even if two get traded, you still end up with too many players, meaning that three need to either optioned or traded to get to the number down to a 25 man roster.