A struggling offense that can't compensate for an inconsistent bullpen and a six-man starting rotation whose depth is being tested have hurt the Mets.
Wilson Ramos hit a grand slam and rookie right-hander Taylor Jordan had six strong innings for his first major league win to lead the Washington Nationals to a 14-1 rout of the Mets on Sunday.
New York took the first game of the series 11-0 on Friday, the first game of a doubleheader.
It was outscored 20-3 over the next three games and once again fell 10 games under .500 at 46-56. The Mets had won five of their first eight after the All-Star break.
"It's kind of a constant thing we've fought for a lot of the year is the lack of run production, but we've been winning games because we've pitched," New York manager Terry Collins said.
"When you get way behind, you can't be very aggressive on the base paths and that kind of changes the way you play."
Mets right-hander Carlos Torres (1-2) could not build on his solid start last week against the Atlanta Braves.
He allowed eight runs and nine hits in just three innings. Ramos had his third-inning grand slam. He ripped a 2-1 pitch into the left-field stands to cap a five-run inning. New York needed four relievers to finish the game.
That's far from ideal with a three-game series beginning Monday in Miami.
"That's where I need to step up and eat up more innings if a situation like that arises again," Torres said. "We still need to get into the next series with a fresher bullpen than we got today."
Jordan (1-3), making his sixth career start, earned his first victory. The 24-year-old held New York to five hits in six innings. The only Mets run came on a fourth-inning single to right by Marlon Byrd. That drove home Eric Young.
Jordan struck out a career-best seven batters and walked just one.
"We want to focus on the first game (Friday), the things we did right, because ultimately that's going get us going in the right direction," Young said. "You think about bad things, that's what's going to be in your brain. You're not going to produce."
Washington won its third game in a row and fourth in five to salvage a roller-coaster 11-game homestand.
It lost the first six games after the All-Star break, fired hitting coach Rick Eckstein last Monday and demoted former closer Drew Storen to Triple-A Syracuse on Friday.
"I think we all know what this group is capable of and what kind of people we have in here," said third baseman Ryan Zimmerman, whose team won a major-league best 98 games in 2012.
"That's one of the biggest strengths of this team is not worrying about things that happen, good or bad."
The Nats set season highs in runs and hits (18) and battered Torres. Ramos singled home Ian Desmond in the second inning to start the scoring. Bryce Harper followed two batters later with a two-out single on a 3-2 count that scored two more runs to make it 3-0.
Ramos tied a career high with five RBIs -- the second time this month he's done so. Ramos also had five RBIs on July 4 against Milwaukee. The grand slam was the first of his career.
"(Washington has) also been struggling over there," Collins said. "You know they've got a good club, but when they bounce back like that, obviously we made some bad pitches."
Notes: Mets third baseman David Wright was not in the starting lineup for just the third time this season It was a non-injury day off, "which he certainly needs," said New York manager Terry Collins. ... Nats pitching coach Steve McCatty was taken to a hospital before the game with what was called atrial fibrillation and high blood pressure. He was expected to remain hospitalized overnight, but will join the team in Detroit on Tuesday. ... On Monday, the Mets continue an eight-game road trip with the start of a three-game series in Miami against the last-place Marlins. ... RHP Jeremy Hefner (4-8, 4.17) pitches for New York against RHP Jacob Turner (3-3, 2.49). ... The Mets are 3-8 against the Marlins this season. ... The Nationals are off on Monday. They begin a five-game road trip on Tuesday in Detroit. ... RHP Stephen Strasburg (5-8, 2.85) starts for Washington against RHP Anibal Sanchez (8-7, 2.68).