The Marlins completed the three game sweep with a 5-0 win on Thursday, outscoring the Nats 22-7.
The outfielders did their best to get on base against a very difficult Ricky Nolasco (13-8).
Roger Bernadina led off the game with a double. Left fielder Willie Harris earned a walk against Nolasco and got a base hit in the seventh off of Jose Veras. Michael Morse had a tough 0-4.
Harris said this shutout loss was similar to what happened to them throughout the series against the Fish.
"We just need to get the pitching and the hitting on the same page at the same time. We are playing pretty good defense. We just couldn't get the big hit tonight.
"I think Livo pitched well enough for us to have a shot to win that game. We didn't score runs. We didn't get big hits when we needed them. That was why we lost the game," Harris said.
The Nats had a chance to get back in the game with Adam Dunn at the plate in the fifth but he struck out with the bases loaded.
Harris on Dunn's at bat down 3-0 in the fifth: "He has been getting big hits for us all year. You can't depend on a guy all the time. Somebody else has to step up every now and again. But he is our guy. We have a lot of faith in him."
The Marlins have now won 8 of the 12 matchups this season and are 34-13 against the Nats since 2008.
Harris said he has been battling the frustration that can creep in when the team gets on a losing streak.
Harris added, "it has been a mental grind for me all year. We have been on a little skid right now and the only way we are going come out of it is we get big hits.
"What good is leading off the inning with a single and we can't get a big hit with a runner in scoring position? That doesn't help us at all. We need to just get big hits and play fundamental defense and we will be fine."
With Bernadina nursing a sore hammy, Jim Riggleman said they will probably give him the day off in the series opener against Arizona.
Justin Maxwell could get the start against the left-hander Joe Saunders Friday and Josh Willingham will be back in the starting lineup after missing two games.