NEW YORK — The 75 human hot dogs came together the way so many New Yorkers do on a sweltering day: sandwiched into the last subway car.

“Who let the dogs out?” one of the group shouted. “Who?! Who?!” the other 74 responded, rhetorically. The train closed its doors and lurched forward.

The hot dogs had convened for a Mets game, where they would serve as one-part mobile pep rally, one-part mustardy entourage for the competitive-eating champion Joey Chestnut. A few minutes earlier the group — tan robes, burgundy hoods, shirts with meandering yellow streaks — had done a hooting lap around the Grand Central concourse, arousing cellphone cameras, and appetites.

“We were told we’d be in a hot-dog flash mob,” one of the hot dogs confided to a reporter. “And who turns down the chance to be in a hot-dog flash mob?”

Chestnut, 35, the reigning king of Nathan’s Hot Dog Eating Contest, had returned to New York to defend his title. For 11 of the past 12 Independence Days he had won the top prize — including last July 4, when he set a record of 74 dogs, meat and bun, consumed in 10 minutes.

On Thursday, he triumphed again with almost embarrassing ease — claiming another $10,000 prize and the coveted mustard belt by devouring 71 hot dogs, three shy of his record but nearly two dozen more than his nearest competitor.

But on Sunday, he had a different mission. Chestnut, a Northern Californian with a placid demeanor, also stars in “The Good, the Bad, the Hungry,” a new ESPN documentary about his surprisingly complex relationship with longtime rival Takeru Kobayashi. And the ESPN marketing machine had gone into overdrive to burnish the hot-dog champion’s image. They arranged to have Chestnut arrive at Citi Field with his sausage posse to throw out the first pitch and later hand out hot dogs — presumably the nonhuman kind.

The walking franks — mostly day-player actors and social-media influencers recruited by a marketing firm called Infinite Agency — piled off the train outside Citi Field.

“We have the hot dogs; we have the hot dogs. Where’s Joey?” an ESPN publicist said urgently into a cellphone, hoping to locate Chestnut, who had arrived a few hours earlier for batting practice. The hot dogs massed boisterously at the top of the subway stairs outside the stadium. “You thirsty? Hot dogs go good with a drink,” a man selling Gatorade out of an Igloo cooler hustled. A half-dozen NYPD officers in SWAT gear stood nearby, unsmiling.

A moment later Chestnut, wearing flip-flops, Nantucket red shorts and a personalized Mets jersey with the number 74, came bounding up the steps.

“Who let the dog out?!” the hot dogs started shouting, semi-musically, to their hero. They surrounded Chestnut as he held aloft the mustard-yellow belt with the Nathan’s name on it — evidence of his recent feat — and pumped it in the air. The singing group encircled him as they made their way toward the stadium, Joseph and his nitrate-y brothers.

Just inside the stadium stood Jelani Wheeler and Zack Becker, from the Mets marketing and communications departments. Wheeler carried a crown made entirely of fake hot dogs. Becker palmed the ball that Chestnut would throw. “We should have the catcher use a bun instead of a glove,” he said.

The hot dogs entered the stadium and were dispatched to their seats up the first base line. But Chestnut was led into a green room in the stadium’s bowels, a great honor signaled by the name on the plate of the adjacent room: “Mr. Met.”

Chestnut had spent the past few months training intensely. This consisted not just of eating large quantities of cured meats but fasting and consuming proteins to stretch his stomach, a regimen that flips the perception of the hot-dog contest as an ­exercise in gluttony to an act of discipline.

Chestnut planned on eating some hot dogs in the days before the competition “just to get in rhythm.” But he wouldn’t eat anything from New York City street vendors. “They’re boiled, and we compete with grilled.”

Chestnut would not answer the big question — he’s not one to philosophize about the larger point of competitive eating nor his motivation for dominating it as opposed to, say, any of the hundreds of more common (and less caloric) life goals. But he let slip that a lot of his desire comes from the knowledge others might do better.

“I never thought I could eat 60. But then Kobayashi ate 54 so I knew I had to top him,” he said. “Right now, if you asked me if I could eat 85, I’d say no. And I probably couldn’t. But if someone ate 84 tomorrow, I bet I could do it.” The human body is a strange machine; it responds to emotion as much as anatomy.

The Mets staffers took Chestnut to a private stadium dining area with an elaborate buffet. He opted for a bun and a hot dog, and paused between bites to share his assessment of the new documentary, directed by Nicole Lucas Haimes.

“I think it was mostly even but maybe a little more pro-Kobayashi,” Chestnut said. The Japanese-born star had split from the sport’s governing body, Major League Eating, over an alleged contract disagreement, but Chestnut was skeptical. “It was all the same stuff he didn’t have a problem with when he was winning. And now he has a problem with it?”

The two, it seems, have beef.

The Mets staffers led Chestnut out to the field as a teenage choir sung the anthem. Mets outfielder Michael Conforto, 215 pounds of ripped muscle, walked up to Chestnut and told him he’d be catching the pitch, then asked him about his training regimen.

The crowd cheered loudly as Chestnut took the mound. Before the pitch, he quickly scarfed down another hot dog that seemed to materialize in his hand from out of nowhere. “I wish I competed in a place this nice,” he ruminated as he came off the mound, the crowd still cheering.

Chestnut’s lionization in a venue that not long ago hosted a World Series might seem odd. But at the end of the day, attempting to hit a cowhide-stitched sphere so that it falls untouched on a grass field is not inherently more logical than seeing how much chemically congealed meat your stomach can accommodate.

Back at the stadium club, members of the teen choir chattered excitedly. One spotted Chestnut and asked for a photo, and soon dozens of teenagers were jostling to be in a group shot, even though many did not seem to know who Chestnut was.

“This is Joey Chestnut,” a teacher explained. “He ate 74 hot dogs in one sitting.”

“That’s a lot of hot dogs,” one teenager mused.

The Mets reps took Chestnut to a private elevator and up to the stands where the hot dogs were all sitting. Dominating a stadium section in that way, the mob cut a striking image, like the world’s most carnivorous church group.

Chestnut chose a seat in an empty row set back from the others and quietly consumed another hot dog, unbothered. But soon fans began recognizing him and approached for selfies and enthusiastic well-wishes. There is no hero like the hero of the picnic table.

Chestnut engaged them all, listening to stories of their favorite condiments, or the time they ate four hot dogs at a family barbecue. He smiled politely at these boasts, the way Babe Ruth might upon hearing about your Wiffle ball achievements.

After a while, Mr. Met arrived carrying a platter piled high with hot dogs. The idea was to hand them out to fans in the stands between innings. (Many of the human hot dogs had already bought pizzas and chicken wings.)

But Noah Syndergaard, the Mets fireballer, suddenly got into trouble. He gave up a hit, then another. Soon a two-out rally had broken out. More batters came to the plate. The ESPN staffers grew nervous — the hot dogs were getting cold. Mr. Met rocked back and forth on his oversize cleats, trying not to drop the tray. Chestnut sat quietly and ate another hot dog.