NEW YORK — In the video, Pete Alonso and Dominic Smith appear to be delirious with joy. Alonso has just hit his first major league home run, and his most direct competitor for playing time jumps up and down as Alonso returns to the Mets dugout. They high-five and holler. The moment went viral.

In fact, they were arguing. Smith wanted to congratulate Alonso; Alonso wanted to congratulate Smith.

“Dom started the inning!” says Alonso a week later, referring to Smith’s pinch-hit leadoff single. “I wouldn’t be put in that position if a bunch of guys didn’t have quality at bats in front of me.”

Finally they settled for just screaming, “Hell yeah!” at each other. Smith had been double-switched in and would be taking over first-base duties. “Lock this down!” Alonso encouraged him. “I got you, Pistol!” Smith replied.

Each one has every reason to trip the other in the batting cage, poison his sunflower seeds, disable his wake-up alarm. There can be only one first baseman at a time, so a setback for one is necessarily a triumph for the other. They don’t see it that way.

“I’m really glad that both of us are on the roster,” Alonso says. “I think we’ve both contributed a lot.”

“We’re a better team with both of us on here,” Smith says.

In fact, through the season's first 11 games, Alonso, 24, is tied for first on the Mets in WAR (0.7); Smith, also 24, slots just behind Noah Syndergaard at 0.2. Alonso’s .878 slugging percentage is third in the NL; Smith, albeit in only 14 plate appearances, is hitting .417. They have combined to give New York the most first base production in the majors, a year after the team finished 28th.

And yet as late as the eve of the season, they did not know their fates. Alonso is a top prospect who had not been called up in September, despite hitting a minors-best 36 home runs across Double-A Binghamton and Triple-A Syracuse last year, in an attempt to manipulate his service time. Many teams now hold prospects down for the first two weeks of April to preserve an additional year of club control; GM Brodie Van Wagenen had promised that the best 25 players would make the roster out of spring training regardless of service-time considerations, but Alonso was unsure what to expect. Smith’s status was similarly unclear. He had played sparingly in the majors in 2017 and ’18, but his assignment seemed to depend on Alonso’s; how could there possibly be room for both of them in Queens?

So when manager Mickey Callaway reshuffled the batting-practice groups before the final workout, players wondered why. He clustered Alonso, Smith, utilityman J.D. Davis, shortstop Luis Guillorme and catcher Tomas Nido, five players on the bubble.

Callaway called the players together and explained that he had grouped them because there was a flight leaving Reagan International for Syracuse in an hour and a half. He paused and watched their hearts sink. Then he grinned. “All you guys are gonna miss the flight,” he said. “Because all you guys are big leaguers.”

Jim McIsaac/Getty Images

It was an easy choice, the Mets said afterward. In fact, Alonso and Smith, thinking there was only one roster spot available, had agreed that spring to make the decision difficult for their boss. They lockered next to each other in Port St. Lucie, Fla.—as they do in Queens—and celebrated both men’s successes. All spring, and even after the team headed north, they offered each other tips. Alonso, the stronger hitter, helps Smith adjust his hands and approach at the plate; Smith discusses fielding with Alonso.

Their friendship has helped them in less tangible ways, too. Along with Davis, 25, and utilityman Jeff McNeil, 27, they form part of a young core. All but Smith are rookies, and all sometimes find themselves wide-eyed by the experience. They dined together at Nusr-Et steakhouse, after a recent game in Miami, and discussed life in the big leagues. (“We had the meat sweats going after, like, two bites,” says Davis.

Alonso has struggled at times with remaining consistent emotionally. Coming out of college, where even the best teams play at most 70 games a season, he had trouble adapting to the grind of a professional schedule. Every game matters … but it also doesn’t. Smith has helped him learn to erase a performance from his head by the time it hits the pillow.

“If I’m a little out of it approach-wise, trying to do too much, he’ll bring me back,” Alonso says. “We’re each other’s leashes.”

Smith loves his friend’s work ethic, coupled with his reputation as a goofball. For the most part, Alonso has started and Smith has come off the bench, but they keep each other engaged.

“What sometimes gets lost when you get to the big leagues is the fun you have,” Smith says. “We’re taking the minor league approach and bringing it to the big leagues, as far as the energy, the excitement, just the fun that we’re having.”

Callaway has noticed. One of the delights for him in this young season, he says, is to watch the young players enjoy it. He points to that home run as an example, but also another moment.

After they learned they had made the team, Alonso and Smith beamed and contemplated their good fortune. Then they contemplated each other’s, and they hugged.