NEW YORK -- One hundred forty-four games into the season, the Mets finally suffered their first series sweep of at least three games.

The optimist might look at that fact and deduce, accurately, that the Mets are in first place and cruising toward a playoff spot. But outside the walls of the home clubhouse at Citi Field on Wednesday, optimists were difficult to find following the Mets’ 6-3 loss to the Cubs. Pessimism was more the cocktail of choice for those who watched the Mets drop seven of their last 12 games against sub-.500 teams. Cynicism had its backers, too.

Folks in those camps trumpeted a fair point. The Mets are healthy and regularly playing some of the worst teams in the National League, but their problems are not dissipating. For the third consecutive game, New York scored three or fewer runs, despite a pregame meeting that manager Buck Showalter and hitting coach Eric Chavez hoped might aid the mental state of the team. This time, boos rained down early in Queens, beginning in the top of the first, when David Peterson faced six batters, walked three of them and retired only one member of the Cubs, who entered the series 24 games below .500.

By the end of the inning, the Mets were in a six-run hole. Peterson left the field to a mix of jeers and general unpleasantness from a crowd of 28,522 -- modest in size, if not demeanor.

“It sucks,” Peterson said. “This one’s on me. I put us in a hole early, and I put us in a tough spot, and I’m going to have to learn from it and be better.”

About the only thing that went right for the Mets occurred on the opposite coast, where the Braves lost for the fourth time in five games following an eight-game winning streak. That allowed New York to maintain its half-game advantage in the NL East, at least for another day.

But the blueprint to stay in first has grown more complex. Once their upcoming four-game set against the Pirates concludes this weekend, the Mets will no longer hold a schedule advantage over the Braves, who are slated to face the last-place Nationals while the Mets head to Milwaukee for a series against the contending Brewers. Everything may well come down to a three-game showdown between the Mets and Braves in Atlanta, beginning Sept. 30.

So long as that series remains relevant for the division title, the Mets will be in a fine situation.

“It’s there for us,” Showalter said, echoing his comments from the pregame meeting with Chavez. “It’s still there for us. We control it. That would be frustrating if we didn’t. It’s the old thing that we’ve been talking about all year. It’s called, ‘Play better.’”

“We’ve got to respect our opponent,” added shortstop Francisco Lindor, who hit into an eighth-inning double play that minimized the damage of the Pete Alonso homer that followed. “Hats off to the Cubs. They came in. They played well. They executed. They pitched well. They hit with people on base. They walked. They played better than us. So hats off to them.”

For the Mets, reasons exist to remain hopeful. They still have four games on tap against the Pirates, whom they beat in a series just last week. They remain one of only two clubs, along with Atlanta, to avoid losing more than three games in a row at any point this season. The Mets have Max Scherzer likely coming off the injured list on Monday and, even if the Braves do surpass them over the final three weeks of this season, New York is something close to a mortal lock to qualify for the postseason.

At times this month, it just hasn’t seemed that way. Reminded pregame that his team still holds greater than a 99.9% chance to make the playoffs, Showalter drew his face into a grimace before launching into a discussion about the grind of the season and “the mental and emotional well” from which the Mets have drawn inspiration. He spoke about the importance of his players not feeling sorry for themselves, and why should they?

For now, the Mets are still in first place, still in control of their own baseball destiny.

“It’s nothing,” Showalter said, “we’re not capable of doing.”