NEW YORK -- Juan Soto had already popped up from his stance and taken a couple of steps toward first base by the time home-plate umpire Jeremie Rehak called strike three. Incredulous, Soto turned around and lingered long enough to tell Rehak he thought the pitch was too low. Onto the field from the dugout, Mets manager Carlos Mendoza muttered profanities to himself.

"From my eyes, it looked down, but everybody is saying it was a strike," Soto said. "I was just wrong, maybe. He made good pitches. He was nibbling around the strike zone. I got a couple of pitches to do damage, and I just couldn't. I just couldn't do it."

The aftermath matched the result on Saturday: The New York Mets, a team that should be desperately firming up its grip on a playoff spot, lost 5-3 in 11 innings to the lousy Washington Nationals in maddening fashion.

When trailing after the eighth inning this season, the Mets are 0-66. They came close to becoming Major League Baseball's last team to pull off such a win after Soto's RBI single in the ninth inning tied the score at 3. But the Mets this season are masters of missing opportunities.

In the big picture, the Mets' playoff chances are a product of failing to capitalize on situations. Instead of adding to a lead for the third wild-card spot, they've allowed mediocre teams to catch up to them. The Cincinnati Reds are the latest team on their heels. The Mets hold just a one-game lead over the Reds. Seven games remain.

Up close, the Mets' latest loss revealed season-long concerns of an inability to take advantage of circumstances.

Despite closer Edwin Díaz throwing just seven pitches (all strikes) to record all three outs in the 10th inning, he stayed in the dugout for the 11th inning. Díaz had not pitched since Thursday. Before that, Díaz, the Mets' closer and best reliever, had three days' rest.

Citing how Díaz warmed up in Friday's game, Mendoza said the right-hander was available for just one inning Saturday.

Instead of pushing Díaz, Mendoza instead used Tyler Rogers, who appeared in his third straight game (he threw a combined 13 pitches in the prior two appearances).

Rogers ended up allowing Daylen Lile's two-run inside-the-park home run, which was ultimately the difference. Lile hit the ball 401 feet to center field with a 104.8 mph exit velocity. It was a good shot. Mets center fielder Cedric Mullins was unlikely to ever catch it. But the issue was with how he played it. He chased after the ball, getting so close to the wall that he had no chance to play it off the bounce. It was so obvious that Nationals third-base coach Ricky Gutierrez started waving home Lile, a speedster, before Lile had even reached second base.

"It's a tough one there," Mendoza said, "but once you realize that you have no chance on that play, maybe you give yourself a better chance to play it off the wall."

If the Mets end up making the playoffs, their inconsistent defense is a concern.

New York gave starter Nolan McLean (five innings, three runs, including one earned) little margin for error because they kept making them. In the second inning, the Mets committed two errors and threw a wild pitch. It was the first time they did so in the same inning since 2003, according to SNY. First, a ball rolled under Soto's glove in right field as he was charging to make a scoop and a throw. Later in the inning, Pete Alonso made a high throw to McLean, who was covering first base.

"I just missed it," Soto said. "I tried to pick it up and make a throw to third base. And I just missed it. My teammates told me, from the side view, it looked like it took a weird hop. But I don't know. I just missed it."

The Mets, at times, make flashy plays -- Francisco Lindor spun and made a terrific throw on a ball that forced him to range to the right of second base -- but too often fail at fundamentals.

"We've been inconsistent," Mendoza said. "We go through stretches where we make plays, we play clean, and then we've been through stretches where that happens."

Another worry if the Mets make the postseason is their failure to win a game after trailing through eight innings.

After Soto's hit in the ninth, Brandon Nimmo and Starling Marte struck out with the bases loaded. In the 10th inning, the Mets had two on and no outs, but Francisco Alvarez grounded into a double play, and Ronny Mauricio lined out to left. In the 11th inning, PJ Poulin indeed dotted the outside corner to strike out Soto with a runner on base to end it.

"It's part of the game, and I know these guys, and they never give up," Soto said when asked about why the Mets have failed to pull off a late comeback. "Nowadays, every team has one or two guys in the back of the bullpen who are nasty."

But this was the Nationals (63-92). In September, the Nationals' bullpen ERA while pitching in the eighth inning or later is 10.02. Washington did what it could to give New York the game, making two errors of its own. Inexplicably, CJ Abrams, the free runner to start the 11th inning, even attempted to advance on a grounder hit in front of him, but Mauricio tagged him for the first out. Playoff teams don't make those kinds of blunders.

They have one week left to not let that be the story of their season.

Mets' failure to capitalize on Nats' mistakes proves costly -- and it's a season-long problem