Both clubs are looking for answers heading into Tuesday night's opener of a three-game series at Nationals Park.
Washington (28-29) owns a losing record for the first time since April 30 after dropping two of three at Atlanta. The Nationals, who are without injured superstar Bryce Harper, hit .190 and totaled seven runs with two walks and 20 strikeouts in the series.
"Half the ballclub is not doing things they're capable of offensively," manager Davey Johnson said. "I look up there, a bunch of guys are hitting .150. There's too good a quality of players here to be doing that. I'm sure we'll pick it up. It's just a tough time."
The Mets (22-32) swept four games last week from their city rival Yankees before heading to Miami over the weekend to face a Marlins team that had dropped a season-worst nine straight. New York batted .212, totaled eight runs and was swept while falling to 3-6 against the majors' worst team.
"Getting swept is not fun especially after sweeping the Yankees and feeling pretty good and then get our butt beat,'' first baseman Ike Davis said.
Johnson is looking forward to the likely return Tuesday by outfielder Jayson Werth, who has been out since May 2 with a strained right hamstring. Werth is hitting .260 with four homers and 10 RBIs in 27 games.
"The offense is just sputtering a little bit," Johnson said. "It'll be good to get Jayson back. ... That'd be a shot in the arm."
"We deserve to be where we're at right now," LaRoche said. "And we're still not in awful shape.
"That only goes so far. We're pretty deep into the season, so we've got to get it going or we won't be there at the end."
Mets manager Terry Collins was encouraged slightly by the production at the plate in Sunday's 11-6 defeat. The slumping Davis, who owns a .272 slugging percentage, drove in three runs and had one of three homers for New York.
"Maybe a couple of guys are breaking out and we'll be better offensively so maybe things are changing," Collins said.
The Mets handed Jordan Zimmermann (8-3, 2.37 ERA) his first loss April 21, as the Nationals starter allowed two runs over a season-low five innings in a 96-pitch effort. He still owns a 1.85 ERA over his last six starts against New York.
David Wright is 9 for 28 with two homers against the right-hander, although the third baseman has one hit in his last 15 at-bats.
Zimmermann had not yielded more than three runs in 15 straight regular-season contests before surrendering seven over six-plus innings in Wednesday's 9-6 defeat at Baltimore.
The Mets had dropped Jeremy Hefner's first nine starts before he gave up three runs over six innings in a 9-4 victory over the Yankees on Wednesday.
Hefner (1-5, 4.74) is 0-3 with a 5.57 ERA in four outings against Washington, and Espinosa is 5 for 10 with two homers and two doubles against the right-hander.