NEW YORK – A Nationals roster loaded with rookies and a bunch of others with only slightly more experience stepped into the cauldron that is Citi Field on a Friday night in late September, recognizing it was going to require both productive and clean baseball to take down a Mets team fighting for its postseason life right now.

They actually got the productive baseball part down, scoring six runs by the fifth inning and watching rookie Andrew Alvarez induce a bunch of ground balls out of the most imposing lineup he’s faced so far in the majors.

They didn’t come close to getting the clean baseball part down, and that’s ultimately was cost them during a 12-6 loss to New York in which they very much looked the part of a 92-loss team crawling toward the finish line nine days from now.

Committing three errors to go along with several other sloppy plays in the field, the Nationals helped make life a whole lot easier for the Mets, who needed this win to maintain a two-game lead over the Reds (who beat the Cubs tonight) for the final Wild Card berth in the National League. (The Diamondbacks also can remain within two games if they beat the Phillies later tonight.)

Whether this one ballgame before a boisterous crowd of 39,484 proves these Nats aren’t yet ready for this kind of spotlight is debatable. Either way, they didn’t come close to putting their best foot forward on a night that demanded a much better brand of baseball for them to emerge victorious.

"It didn't come our way, but it happens," interim manager Miguel Cairo said. "And I know they're going to come back tomorrow and fight again. But that was the atmosphere that I want them to see. They were playing hard. We scored six runs. It didn't go our way. But tomorrow's another day."

Alvarez’s worst night as a big leaguer ended with six runs and seven hits off him in 3 1/3 innings. But it doesn’t require that much stretching of the imagination to view the rookie’s fourth career start in a much more positive light than those bottom-line numbers suggest.

Two of the six runs scored off Alvarez were unearned. Six of the seven hits he surrendered were singles, and only three of them carried an expected batting average higher than .260. In short, most everything was hit on the ground, and the seven defenders positioned behind Alvarez didn’t exactly do a bang-up job turning those ground balls into outs.

That includes the Nationals outfield, which had an uncharacteristically miserable night. Dylan Crews was twice charged with an error when he failed to cleanly scoop a groundball single to right, allowing runners to take extra bases off him (and ultimately, in each case, score). James Wood (who also struck out twice to raise his season total to 212, only 11 shy of Mark Reynolds’ major league record) did the same thing on a groundball single to left in the fourth, though this one came after Alvarez had departed.

"I kind of rushed it a little bit," Crews said. "That usually doesn't happen. Maybe rushed it. I've just got to slow down a little bit, make sure I've got the ball first and make a good throw."

Regardless, this wound up the first time Alvarez gave up more than two runs or three hits since his promotion. And with his pitch count already up to 81, he wasn’t given the opportunity to face the Mets lineup a third time.

"Just falling behind in counts, throwing a lot of pitches early and obviously putting a lot of stress on the bullpen and obviously not leaving the game in a good situation," he said. "It's just frustrating. Sometimes those ground balls are hit right at guys. Tonight, they just found holes and whatnot. But I'd feel a lot better just getting ahead early."

Not that the guy who replaced Alvarez fared any better. In fact, he fared worse. Much, much worse.

PJ Poulin entered with two on and one out in the fourth and immediately surrendered an RBI single to Francisco Lindor (the single that Wood booted in left field for his error). Then the rookie lefty put a sweeper over the zone to Juan Soto and paid a dear price for it: a three-run homer to center that was only a few feet short of landing inside the Citi Field big apple.

Thus did the Mets score six runs in the span of seven batters in the bottom of the fourth, turning a 4-2 deficit into an 8-4 lead, with way too much baseball still to be played.

"That's the best hitter in the big leagues," Cairo said of Soto, who also singled and walked twice. "He left something over the middle, and he made you pay. You've got to execute your pitches."

The Nationals took their lead with an impressive rally of their own, plating four runs in the top of the third after an awfully quiet opening two frames. Unable to hit the ball out of the infield initially against Brandon Sproat, they figured something out after that and strung together a bunch of quality at-bats against the Mets rookie to knock him out of the game earlier than anyone in Flushing wanted.

The bottom of the order ran the table with two walks and a single, that single coming in the form of Jorge Alfaro’s dribbler just down the third base line, with Sproat fielding the ball and then throwing it off Alfaro’s back as he approached first. Paul DeJong came all the way around from first to score on a play that looked almost identical to the infamous Trea Turner interference play from the 2019 World Series. The only difference: It’s now legal for a batter-runner to be in fair territory, provided he’s still on the dirt as Alfaro was.

The big hits came in succession later in the third, with CJ Abrams, Josh Bell and Daylen Lile each delivering extra-base hits, including Lile’s 11th triple of the season on a line drive just to the right of center field that got past Jose Siri and rolled to the wall. Lile coasted into third having tied Denard Span’s single-season club record, the 22-year-old rookie having done it in a mere 84 games.

"We made some adjustments right away, and you saw it," Cairo said of the approach against Sproat. "That first inning, he chose the way he was going to pitch. We made an adjustment, and we got a chance to score some runs and take him out real quick."

Abrams would deliver another big hit two innings later, driving a changeup from reliever Huascar Brazobán some 426 feet to right-center for his 18th homer, trimming the 8-4 deficit into an 8-6 margin with four innings still to play.

The Mets would tack on one insurance run in the seventh off Jackson Rutledge and three more in the eighth off Mason Thompson, turning a once-competitive game into a rout over a young team that didn't look ready for prime time.

"Obviously, the team wishes we could be in that (situation), coming down the stretch fighting for a Wild Card," Alvarez said. "But it didn't change how we wanted to play. We wanted to go out there and win."