NEW YORK -- Francisco Lindor’s first swing was a sizable one, cutting underneath a 95.2 mph Giovanny Gallegos fastball. His next swing was a foul ball to stay alive in his ninth-inning battle with Gallegos. His third and final swing caught nothing but air, as another fastball ran toward the outer edge of the strike zone.

For Lindor, it was the lone strikeout of a long Tuesday at Citi Field. But it was a significant one, coming in his final at-bat of the night with the potential tying and winning runs on base. Rather than complete another comeback, the Mets settled for a doubleheader split with the Cardinals, losing the nightcap, 4-3, after taking the matinee, 3-1.

Lindor finished 1-for-7 with two walks in the games, dragging his season slash line down to .228/.315/.393. And that’s been a familiar story for Lindor since coming to New York.

Lindor, 2015-20 with Cleveland: .285/.346/.488

Lindor, 2021-22 with the Mets: .229/.322/.407

The sample size is growing large enough to be meaningful. Tuesday’s games were Lindor’s 162nd and 163rd with the Mets, representing a full season. (He missed roughly five weeks last year due to an oblique strain.) Although Lindor showed some pluck at the beginning of this campaign, he has since hit .160/.239/.259 over his past 21 games.

“I’ve got to do whatever it takes to keep on grinding, keep on working, keep my head down and leave the rest to God,” Lindor said. “I can only control how I go about my process and what I do during that process. And after that, I leave everything to God.”

Whether fairly or not, the weight of expectations will continue to bear down upon Lindor because he is one of the most handsomely paid players in the history of the sport, now in the first season of a 10-year contract extension that will pay him $34.1 million annually through 2031. (The $341 million extension, which Lindor signed before last Opening Day, did not officially kick in until this year.)

Entering the season, many around Flushing hoped Lindor would follow the career arc of Carlos Beltrán, who struggled upon signing his megadeal with the Mets before blossoming in Year 2. And for a brief moment, Lindor looked game to play the part, mashing eight extra-base hits with a 1.035 OPS over his first 14 games.

Since that time, Lindor’s strikeout rate has more than doubled from 11.3 to 23.6 percent, while his walk rate has nearly halved from 14.5 to 7.5 percent. He has once again begun to hear boos at Citi Field, and not only because of his offense; Lindor also entered Tuesday’s play with four errors and a career-worst -4 defensive runs saved figure at shortstop.

“This game’s hard,” teammate Brandon Nimmo said. “We all know it. Having the experience we have on this team allows us to help each other and pick each other up when things are not going as well for one of us. … There’s no more pressure on Francisco or anything. We take this pressure on as a team. We win as a team and we lose as a team.”

Lindor’s struggles have stood out in recent days for precisely that reason: the Mets are no longer winning with consistency. Tuesday’s doubleheader split moved New York to 6-6 over its past 12 games.

Then there is the matter of Andrés Giménez, the spark plug infielder whom the Mets traded, along with Amed Rosario and two prospects, to Cleveland in January 2021. All Giménez has done over 31 games this season is hit .323/.340/.552 with 12 extra-base hits, making good on the potential that Mets officials long saw in him.

This is not, in short, the way anyone around Queens wanted the marriage to Lindor to go. But it’s important to note that there’s still plenty of time -- most of a decade, really -- for him to turn things around.

“I don’t worry about him,” Mets manager Buck Showalter said. “He’s a good shortstop, playing with great effort, engaged in every game, every inning. I’m real happy with him.”

When asked about his struggles, Lindor noted the quality of opponents he’s been facing, quipping that “pitchers have nice cars, too.” He grew more introspective when asked how he feels compared to the beginning of the season, pausing for eight full seconds before answering.

“It’s tough to say right now,” Lindor finally replied. “I just struck out to finish the game. If you would have asked me [after] the first game, it would have been a different answer."