Right after the final buzzer sounded on Game 7 between the Milwaukee Bucks and the Nets during the N.B.A.’s Eastern Conference semifinals last spring, Giovannie Cruz had to leave his house in Elizabeth, N.J., and go to a nearby park. Cruz, an avowed Nets fan for most of his 39 years, had watched the game with his 4-year-old son and “acted like a lunatic” until the end, when the Nets lost in heartbreaking fashion.

“I literally walked around that park for almost an hour from the sheer disappointment,” Cruz said. “I didn’t want my son to see me too animated and use too much colorful language.”

Last season was supposed to be year, the season when the Nets and their fans — both the long suffering and the newcomers — would no longer be an afterthought in the N.B.A. The last time a pro sports team from Brooklyn won a championship, Jackie Robinson was wearing a uniform for the Dodgers in Major League Baseball. It was 1955.

But there was more at stake for the Nets last season than simply winning a championship. In a city dominated by Knicks fans, a title could have allowed the Nets to plant a basketball-shaped flag (and raise a banner) in their efforts to shift the balance of power away from Madison Square Garden and put Knicks fans in their place. Just ask one of the Nets’ most prominent backers, the mayor of New York.

“I really feel like this is the final act in the renaissance of Brooklyn and giving Brooklyn its rightful place in the world, and that has tremendous importance for the city going forward,” Mayor Bill de Blasio, a longtime Brooklyn resident before his 2014 inauguration, said in an interview before Game 3 of the semifinals series, when the Nets were up 2-0 and a championship run seemed inevitable.

The renaissance will have to wait. This summer, the Nets retooled their roster, somehow managing to add talent to one of the best on-paper assemblies in N.B.A. history. With veterans like Patty Mills and Paul Millsap now coming off the bench and healthy versions of Kevin Durant and James Harden ready to take the floor, the expectations for the Nets will be sky high. That’s true even if Kyrie Irving, barred from games until he gets vaccinated, doesn’t play for a while. But if the Nets don’t win at least one ring, this era most likely will be considered one of the biggest flops ever — and the Nets will have blown their best chance to cut into the suddenly resurgent Knicks’ hold on the city.

“We don’t want to be just the most popular N.B.A. team in New York City,” John Abbamondi, the chief executive of the Nets, said in an interview at Barclays before that Game 7. “We want to be a global sporting icon on the level of a Real Madrid of Barcelona. That’s our aspiration.”

Nine years ago, the Nets played their first season in Brooklyn, after being in New Jersey since 1977 following the merger with the A.B.A. The team had some success with the fast-paced teams of Jason Kidd, Richard Jefferson and Kenyon Martin in the early 2000s, but it spent most of its history in the basketball wilderness, rarely attracting stars or playing in important games.

“It was kind of rough at that time,” said Trenton Hassell, a guard who ended his career with the Nets in New Jersey from 2008 to 2010. “We had true fans still coming, but we were doing a lot of losing so that was tough.”

Moving to Brooklyn was a new start on many levels. They had a shiny new arena, new branding and a spotlight-grabbing minority owner in Jay-Z, who was often on the sidelines with his megastar wife, Beyoncé.

Old and new Nets fans are blending and forging a new collective identity. The cheers at Barclays Center are often most prominent from 96 or so fans who sit in Section 114. The die-hards there, called the Brooklyn Brigades, are sponsored by the team and are known for their creative chants. That’s a far cry from the early days in Brooklyn, when rival fans often outnumbered those of the Nets and Barclays had middling attendance overall.

Richard Bearak has been a Nets fan since the 1970s and was at the championship in 1976. He’s the director of land use for Eric Adams, who is the Brooklyn borough president and the Democratic nominee for mayor of New York City. When Barclays first opened to the public, Bearak said, the arena was a “tourist attraction” that drew fans of winning, opposing teams.

“A third of the crowd could have been supporting Golden State,” Bearak, 63, said. “At Madison Square Garden, it’s really hard to be a fan of another team and expect to be there in droves.”

When the Nets first arrived from the Meadlowands in 2012, they did so as an interloper in some eyes. First, there were the fans in New Jersey who resented losing their team. And in Brooklyn, there were those who believed Barclays, which was part of a $6 billion commercial and residential redevelopment, would do more harm to the area than good — particularly with concerns about gentrification and congestion.

A 2014 study by The New York Times based on Facebook data showed that after two seasons in Brooklyn, the Knicks were the more popular team in every New York City ZIP code, except the neighborhoods surrounding Barclays — in part because of the new residents who had moved to the remade downtown area. In response, the Village Voice referred to the Nets as “Gentrification’s Team.”

“We didn’t have a fan base for New York or Brooklyn at all,” said Irina Pavlova, then a top executive with the company of the team’s owner at the time, Mikhail Prokhorov. “It was zero. It was starting from scratch, especially in a city like New York, where the Knicks are such an institution.”

Pavlova said the franchise focused on using “Brooklyn” as the main calling card to recruit new fans instead of the team name, as other franchises do. The fruits of that marketing effort can still be seen today, when the most common team chant is a drawn out “Broooooklyn!”

“That was done to appeal to the residents of the borough since they didn’t have a team to root for,” Pavlova said.

The people cheering for the Nets these days can generally be placed in four boxes. 1. Fans since the Nets were in the A.B.A. and playing in Long Island, like Bearak. 2. New Jersey-era fans like Cruz. 3. New, Brooklyn-era fans. 4. Those who root for specific stars, no matter their team.

That last group is the hardest to track and may be the most crucial for the future of the Nets in the N.B.A., where star players are more influential than in other team sports. Irving, Durant and Harden brought in an uncertain number of transient fans. In the first and second halves of last season, the A-list trio had three of the league’s 10 highest selling jerseys.

Dawn Risueno, 53, a lifelong Brooklyn resident, became a Nets fan in 1990 because her ex-boyfriend preferred them over the Knicks.

She has spent several years following the team across the country as part of an annual road trip. She converted her sports-agnostic husband of 18 years to the cause, and brought along her two children and seven grandchildren.

“They didn't have a choice in the matter,” Risueno said of her children and grandchildren. “Since they came literally out of the womb, I’ve had them in Nets outfits.”

Bobby Edemeka, 46, a portfolio manager who was born and raised in Brooklyn, said he used to follow players instead of teams. But the Nets’ relocation to his hometown instilled pride, and Edemeka founded the Brooklyn Brigades group, which was unofficial until the Nets began sponsoring it in 2018. (Edemeka used to buy bundles of tickets and offer them for free to prospective Nets fans.)

“You can travel the whole world and you’re not going to find people more proud of where they’re from than New Yorkers, and I think that goes especially so for people from Brooklyn,” Edemeka said.

For pre-Brooklyn fans like Cruz, loving the team means “waiting for the bottom to fall out at all times.” Cruz lived through the 2009-10 season, when the team went 12-70. Still, Cruz was upset to see the Nets leave New Jersey two years later. He kept rooting for the team nonetheless. Many New Jerseyans didn’t.

For newer fans like Edemeka, their Nets memories are mostly highlights. The team has made the playoffs in six of its nine seasons at Barclays. There have been two playoff series wins. There hasn’t actually been much suffering, all things considered.

“I don’t have any of that emotional baggage,” said Edemeka, a season-ticket holder for all of the Nets seasons. “I didn’t live through 12 and 70. I’m unburdened by that legacy.”

Old Nets fans and all but the newest Knicks fans know a thing or two about emotional baggage. And yet the relative success of the Nets in Brooklyn, alongside the mostly dreary days at Madison Square Garden during the same period, has not broken the city’s devotion to the Knicks.

There is, in theory, a concrete way to close that gap. Fans go further to associate themselves with winners, as documented in a landmark fan behavior study by Robert B. Cialdini in 1976 — a psychological concept known as “basking in reflected glory.” The opposite — disassociating from losing teams — is known as “cutting off reflected failure.” The study found that fans are likely to say “we” in reference to their favorite team’s winning but “they” if the team loses.

Rick Burton, a professor of sports management at Syracuse University, said that if the Knicks remained the more inept team, younger generations in the city not yet dug in on team allegiances may precipitate a cultural shift.

“The Knicks could rule almost by default,” Burton said of the Knicks before 2012. “But with social media, 500 television channels, a million websites, Brooklyn is not that far from any of the other boroughs, suddenly we have to talk about the fact that the Nets appear to have much more of a cachet than the Knicks.”

But the flip side to that is, of course, not winning, which the Nets are intimately familiar with. The promising, but ultimately deflating, semifinal series last season showed that.

“It’s always been so hard to be a Nets fan,” Cruz said.