WASHINGTON -- Of all the statistical inequalities the Mets have endured this season, one in particular is at least as striking as the rest. Eleven times this season, the Mets have allowed a grand slam. Not once have they hit one.
Such was the script for their fate on Monday, when Danny Espinosa launched his first career grand slam off Ryota Igarashi in the sixth inning, sending the Mets to a 13-3 loss at Nationals Park.
Asked to explain Igarashi's struggles, manager Jerry Manuel simply shrugged.
"I have no clue," he said.
On a Labor Day in which the Mets and Nats most certainly labored, using a combined 36 players and throwing a combined 317 pitches, Espinosa's blow was most memorable. Three innings after Espinosa homered off Mets starter Mike Pelfrey, the rookie launched an Igarashi fastball over the right-field wall for his grand slam, his third career homer and his second of the game.
That turned a five-run game into a nine-run blowout, putting the Mets well on their way to their sixth loss in their past eight games.
"I was trying to see a good pitch up [in the strike zone], and I got couple of pitches up that I was able to drive," Espinosa said. "It went my way today."
Although Igarashi served up the loudest crack, he was not the primary culprit in this loss. That misfortune went to Pelfrey, who -- after a fine August in which he ranked among the league's top pitchers in several categories -- submitted his second straight inadequate outing in September.
After a breezy first few innings, Pelfrey lost his fastball command in the fourth, walking three batters, allowing Ivan Rodriguez's two-run double and Nyjer Morgan's RBI single, and soon after was trudging off the mound with his eyes to the ground.
"I firmly believe that it comes down to the fastball," catcher Josh Thole said. "When you lose a feel for your fastball, it's hard to pitch on your offspeed stuff."
By the time Pelfrey was through, he had given up six runs on five hits and three walks, striking out one. And so after a fantastic April and May, a decent June, a horrendous July and a stellar August, Pelfrey has begun to struggle. Again.
"I guess you'd have to say he is an enigma at this point," Manuel said. "It's kind of hard even for us to figure out. Early on, you see good stuff. You see good presentation. And then you see him kind of spinning and losing control and losing command, and then obviously confidence, and he can't get it back."
That, for Pelfrey -- retaining confidence -- has been most difficult. Though teammates and opponents alike have lauded his pitches as some of the best in the game, Pelfrey, in more than four big league seasons, has been utterly unable to harness them with any consistency.
In the past, Manuel, Pelfrey and pitching coach Dan Warthen have described the right-hander's struggles as equally mental and physical. But after Monday's loss, Manuel indicated that the bulk of Pelfrey's issues are lodged somewhere in his brain.
"I just see a guy that kind of loses confidence," Manuel said. "I see a guy that doesn't have the presence on the mound."
So it was Monday, when Pelfrey began the sun-splashed afternoon throwing strikes before losing his feel for the strike zone in the middle innings. Standing on the mound waiting to give the ball to reliever Raul Valdes in the fourth, Pelfrey's body language betrayed him.
"I don't think you can walk three guys in an inning ... and expect good things to happen," Pelfrey said. "I lost my command in that inning, and before I was able to get it back, the damage was already done."
Espinosa's blast off Igarashi then ensured that the Mets would not undo it. Though they did rap out three early runs against Nationals starter Jordan Zimmermann, scoring on David Wright's sacrifice fly in the first, Thole's bases-loaded walk later that inning and Thole's RBI single in the third, the Mets did not record a hit off reliever Scott Olsen, who tossed four innings.
By the ninth, players such as Nick Evans, Mike Nickeas and -- believe it -- Oliver Perez were in the game, while Wright, Angel Pagan and Pelfrey were sitting on the bench. This was not what the Mets had in mind for their Labor Day. But not much this season has gone according to plan.
Especially not for Pelfrey.
"He's still somewhat of a young pitcher," Manuel said. "And the more times that he goes out there, I think, the more times he will get better. He just has to keep going out there and keep battling these things until he gets better. He's a guy that has a tremendous arm, a tremendous upside -- we've seen it. We've got to keep pushing him out there."
Anthony DiComo is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.