NEW YORK — On the Sunday late afternoon when the long-galloping coolness of the borough of Brooklyn took maybe its loudest stride yet, one of those honorably lonely sorts one might call an “ardent Nets fan” sat over in Manhattan on a bench in Central Park. He read his phone. He saw the news. He craved a rapturous scream but refrained.

He just had to get to Brooklyn before sundown for primo photo possibilities. He mounted his bike and made an hour-long meander south toward his home near the tip of Manhattan, a path complicated by the barricades of the gigantic LGBT pride parade downtown. He parked the bike and got a subway under the East River toward the tangle of train lines beneath the Brooklyn Nets’ home, the seven-year-old Barclays Center.

He emerged and found no other ardent Nets fans, the kind of classic Nets twist bound to change now that Kevin Durant and Kyrie Irving have chosen Brooklyn over Manhattan and all else. “Honestly, I thought a lot more people were going to be here,” said Jeff Liu, 31, who followed the Nets since they were the New Jersey Nets in his Garden State childhood. “I guess people haven’t really caught on or don’t care as much. And the Knicks have a bigger following. But next year there are going to be a lot more people.”

“Honestly,” he said, “I thought it would have been not just me.”

Soon a dude walked by, saw Liu’s Brooklyn jersey, high-fived him, exclaimed: “K.D., baby! Let’s go!” — then continued on.

“I have no idea who that is,” Liu said.

Squint down Atlantic or Flatbush, and one might imagine a bandwagon forming in the distance. All the entrenched basketball meanings in the city just went upturned. “If Brooklyn even comes up with something even close to a victory and wins this,” radio host Mike Francesa had said on Friday, “that would be such an amazing accomplishment and such a thundering blow to the Knicks.” The New York Post headlined it with the rare NOTHING BUT NETS with “Knicks nightmare” in the subhead, and the New York Daily News lampooned the Knicks’ “mecca” of Madison Square Garden with THE MECCA over a photo of — what? — Barclays Center.

That Barclays Center, above the convergence of the 2, 3, 4, 5, B, Q, D, N and R trains, and across the street from the kind of immaculate mall of chain giants that epitomizes Brooklyn gentrification, figures to change its NBA tenor. It figures to become a harbor of energy and star-shine, rather than a place people go to ply sane ticket prices into nightlong glimpses of visiting big-name players (such as the Golden State Warriors). And what might become of those sane ticket prices?

Roland Dumar and Junior Kelly, ages 39 and 38, wondered that after they crossed Flatbush Avenue on Sunday evening. In the crosswalk they had wondered about reasons Durant would have left Golden State and $221 million. Native Brooklynites who met at New Utrecht High, they had just gone to get Dumar a Nets cap but found the team store closed.

Yet Kelly wore both a Nets shirt and cap he had donned that morning, so a New York TV crew spotted it across Flatbush through the general desert of Nets gear in the area and hurried across seeking an interview. (He politely declined.) He and Dumar remember a Christmas tree lot on the Barclays land. They remember, of course, when Dumar’s brother ran the barber shop Skilz on the property, before the rent tripled.

“It changes the whole basketball culture,” Dumar said of the signings. He said, “The light is much more bright.” Kelly wondered, “How are they going to keep the tickets at reasonable prices?” Dumar said: “I think K.D.’s attitude, his demeanor, fits for Brooklyn. Because like sometimes how he reacts to things when he gets into certain beefs. He plays with that chip on his shoulder. And that fits. Because that is Brooklyn.”

The early evening felt like some normal summer Sunday. Droves of people stood in lines at Target. Shake Shack was open. The Christmas-like sign shone, introducing 5th Avenue as “Park Slope’s 5th Avenue.” (The other 5th!) A video billboard with rotating ads did boast one in the mix forecasting, “Brooklyn’s Rise Is Inevitable,” featuring a member of the Nets’ 42-40 playoff team that finished up in April, Jarrett Allen, famous LeBron James shot-blocker.

Wait! Another Nets fan! He sat over on the benches up by the big intersection. As a Brooklyn native, Wayne Lurye adopted the Nets in 2012 when they arrived from New Jersey, and he greeted the latest news with a measured approach. “I was happy about it,” he said, “but I’m not jumping up and down.” He, too, thought he might see something forming in the distance, something always ticklish for a fan already devoted: “That’s exactly what it is, there’s a bandwagon,” he said, soon adding without pique: “Yes, I hate that. Pick your team and stick with it. I was a Yankee fan in the ’80s, before [and after] they started winning. . . . I’m expecting it.”

Back across the way, a woman sat on the sidewalk spray-painting a mural on a garage door, a slew of cans beside her. Parade-goers emerged from underground in rainbow gear. Soon, up emerged Liu in a No. 72 “Biggie” jersey, procured in a Nets promotion honoring famous Brooklynites including the late rapper Christopher Wallace, or Notorious B.I.G. “I wear this jersey very proudly right now,” Liu said. “I’m probably going to wear this the whole week!”

He has been used to being the only one, or one of the only two Nets fans at his office at an ad tech company in the World Trade Center. “I’m actually here to take a picture,” he said. “I want to post on Instagram and just welcome K.D. and Kyrie.”

He likes the respect (from the organization) and intimacy of Nets fandom. Like the true fan even a devotee of some woebegone English soccer club could appreciate, he will continue to wish mirth upon the Golden State-bound D’Angelo Russell. Liu and his girlfriend signed on for two more years of season tickets at a sedate $2,300 each for 41 home games in 2019-20 and 41 more at $2,100 for 2020-21. Where once Nets fans might wish to sell single-game tickets at face value now and then but couldn’t find buyers, now they’ll be able to find buyers but won’t want to sell.

It always bothered him, those 50-50 crowds with visiting teams welcomed too warmly. Now, that figures to tilt.

“People who were paying attention understood how well the team and the organization are being run, and the direction,” he said. “But let’s say somebody on the West Coast, they still had this perception. Maybe the Boston trade” for Paul Pierce and Kevin Garnett that led to brief spasms of joy amid continued ennui. Otherwise someone on the West Coast, for example, might spend ample time forgetting the Nets exist.

“A lot of attention just falls on the Knicks,” he said. “This changes everything. This changes everything.”

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