What makes a terrific sports rivalry? In Philadelphia, we know one when we see it, and for the teams and fans here, it usually, but not always, involves a franchise from that sprawling metropolitan region 90 miles north: New York.

It’s the proximity. It’s the relative, stereotypical contrast between the cities and their fans: New York’s, so smug and self-satisfied, with so many teams and riches and championships to celebrate; Philadelphia’s, always viewing themselves as the underdog.

Eagles fans may derive more satisfaction from their team beating the Cowboys, but the truth is that Eagles-Giants has featured just as many great games and dramatic moments, if not more.

Citizens Bank Park crackles with energy every night that the Mets are in town. And though the Penguins and Sidney Crosby rank as Philadelphia’s Public Hockey Enemy No. 1, the Flyers have lengthy and healthy histories with the Rangers and Islanders that give those games some extra spice.

But that same fevered intensity has never really sizzled and popped between the Sixers and either the Knicks or the Nets, and it’s that context that makes what happened Wednesday night at the Wells Fargo Center so interesting. It wasn’t just that the Sixers beat the intentionally undermanned Nets, 123-117, and gained an edge in the race for the No. 1 seed, and home-court advantage, in the Eastern Conference postseason tournament. It was that there was some mild pre-game trash talk from Ben Simmons. There were “KD SUCKS” chants, directed at street-clothed Kevin Durant, from the 4,100 spectators in the arena. There was the faint flicker of some bad blood between the teams.

“We know exactly who they are, and they know who we are,” Sixers coach Doc Rivers said. “There’s no secrets. Whether they all played tonight and we won or they all didn’t play and we won, it didn’t matter. When the playoffs start, it’s a whole new beast, and we’ll be ready for them, and I’m sure they’ll be ready for us.”

» READ MORE: Ben Simmons raises great points about star-studded Nets. Will Sixers use that to their advantage Wednesday?

The reasons that a fierce Philly-New York NBA rivalry has never materialized are pretty straightforward and obvious. Over the last half-century, the Sixers and Knicks have never been good at the same time. When the Knicks were at their peak – the early 1970s, the mid-to-late 1990s – the Sixers were abjectly awful. When the Sixers have been an excellent or elite team – the late 1970s into the mid-1980s, 2000-01 with Allen Iverson, these last few seasons – the Knicks have been one of the league’s laughingstocks. The Knicks had the Pacers, the Bulls, and the Heat. The Sixers had the Celtics.

The only incident that might have ignited some full-fledged sports hatred between the franchises took place in 1989, when the Knicks swept the Sixers in the playoffs’ first round, rallying to win the series’ final game at the Spectrum. Led by point guard Mark Jackson, they grabbed brooms after the game to emphasize what they’d just done.

“Instead of acting like they’d been there before – because they’d never actually been there before,” said Mike Vaccaro, the longtime New York Post sports columnist, who has a savant’s memory and appreciation of the city’s sports history. “It was ridiculous, and what’s funny is, it wasn’t like it sparked a furor between the cities. It just ticked off the basketball gods. Instead of becoming the Pistons’ heirs in the East, the Knicks were stepped over like Fredo Corleone by the Bulls.”

As for the Nets, with the exception of their back-to-back NBA Finals appearances in 2002 and 2003, they were generally too woebegone to matter. But since the franchise’s move from East Rutherford to Brooklyn in 2012, things between them and the Sixers have gotten a little zestier. The teams brawled and jawed during their five-game series in 2019, and now that the Nets have stocked themselves with Durant, James Harden, and Kyrie Irving, they seem poised to become the primary foil for Joel Embiid, Simmons, and the Sixers. At least for this season. Maybe longer.

“Because they’ve got players who are not homegrown,” John Nash, who was the Sixers’ general manager in the late ’80s and the Nets’ GM in the late ’90s, said in a phone interview. “They’ve come in from other teams. The rivalry that could exist hasn’t really had a chance to ferment and grow.”

It will have that chance this spring, assuming the teams meet in the conference finals, and the dynamic that Nash noted distinguishes them. Embiid and Simmons, the Sixers’ centerpieces, have been here a while. They’ve connected with the city. They plan to stay. The Nets’ stars? Not so much.

» READ MORE: As stars sit out marquee games, the NBA is stealing money from its fans | David Murphy

“Even now, it’s hard to say the Nets represent any fabric of New York because they’re far more of a national team,” Vaccaro said. “They aren’t even close to the most popular team in their own borough. The Knicks may play in Manhattan, but their oldest and most loyal fan base is and always has been Brooklyn.”

So they’re carpetbaggers and mercenaries. They’re inauthentic. They’re arrogant enough to think that they can have their best players sit out important regular-season games and still waltz to a championship. Sounds like the beginning of a beautiful and bitter basketball showdown, one that has been too long in coming.

» READ MORE: Joel Embiid’s outside touch gives opponents a sick feeling on the inside