DALLAS — It was fitting and predictable, given what OG Anunoby has demonstrated in the NBA, that his introduction to the mainstream basketball world was a defensive performance.

Anunoby’s Indiana squad was facing high-powered and high-ranked Kentucky in the second round of the 2016 NCAA Tournament. Just an 18-year-old freshman, Anunoby stifled Jamal Murray, the current Nuggets star, and alternated between guarding 6-foot-11 center Skal Labissiere and 5-9 guard Tyler Ulis.

Anunoby’s defensive positional versatility, the kernel of his value to the Knicks, was on full display.

“Tyler was player of the year in the SEC, and he couldn’t get by OG,” Tom Crean recalled to The Post. “He’s got such a low center of gravity for as big as he is because he stays low. And he can guard multiple dribbles. And what he can really do is change direction.”

Tom Thibodeau and William Wesley were notable attendees at that Indiana-Kentucky matchup.

They sat side-by-side in Des Moines, Iowa, according to Crean, absorbing Anunoby’s breakthrough.

Roughly eight years later, Thibodeau and Wesley, along with Leon Rose, injected the Knicks with a shot of five-star defense by acquiring Anunoby. The numbers speak volumes:

Simply put, Anunoby guards the stars, no matter their position, and provides the Knicks with something they’ve been missing since maybe Latrell Sprewell left town: an elite versatile defender with size, power and quickness. 

“He physically just mugs people,” a scout said. “The right way. Not like [Josh] Hart. Hart has bad feet. So Hart has to tackle you or put his shoulders on you to stop you from getting by you on the second dribble. … Hart is only like a B or B-plus defender [on the perimeter]. Anunoby is an A defender. He’s just bigger. He has the foot quickness to take the right angles. Play bigger guys, play smaller guys. He’s really good.”

Anunoby’s legs tell a lot of the story. They’re like oak tree trunks, massive and powerful. His brother, Chigbo, is a former NFL linebacker, his mother a former track-and-field competitor.

The athletic genes are strong. And so was the discipline growing up, it seems.

“I do not intend to be immodest, but we tried to raise a proper family,” Anunoby’s father, OG Sr., told Sportsnet Canada before he died in 2018 at 66 years old. “And when I say proper, what I mean is we are people who do things well. We value hard work, order, and success. You don’t talk unless you have to talk. And if you have to talk, you should say something that doesn’t take away from the conversation, but enriches it.”

Still, there was no basketball history in Anunoby’s family, and he was hardly a traditional blue-chip, blue-blood prospect. An unranked 3-star prep player, Anunoby wasn’t even recruited by his hometown University of Missouri. Fine-tuning was necessary when he got to Indiana.

So Anunoby and Crean studied film of the elite NBA wing defenders — including, as Anunoby reeled off recently, Kawhi Leonard, Metta World Peace, Andre Roberson, Victor Oladipo and Paul George.

“Those big wing defenders like Jimmy and Kawhi, Paul George, those guys were phenomenal at dropping their shoulders, getting around screens, being able to defend with either hand, using their legs,” Crean said. “And we spent a lot of time on that. And OG really bought into that.”

Added Anunoby, “Kawhi, Jimmy and Roberson were the three that stuck out.”

The film sessions were for tactical and mental preparation. For physical development, Anunoby and the rest of the Hoosiers removed their sneakers and trained in the sand pit, which was built outside of Indiana’s practice facility.

“There are two different ways to do conditioning without putting wear and tear on your body,” Crean said. “Swimming or the sand pit. So we used the sand. And it forces you to get quicker. You got to get lower obviously because your feet are in that sand.”

The idea, beyond the obvious conditioning benefits, was cultivating hip flexibility, adding another physical tool to go with Anuboby’s natural “wrist strength” — which Crean called the second-best he’s ever coached, behind only Anthony Edwards.

“I had a GM before the draft tell me that as a player 6-6 and better, [Anunoby] had the best percentage of on ball defense without fouling,” Crean said.

As the 23rd pick for the Raptors in 2017, Anunoby was thrown into the cauldron. His top-three head-to-head matchups as a primary defender, based on regular-season minutes as a rookie, was LeBron James, Giannis Antetokounmpo and Jayson Tatum. In his maiden playoffs of 2018, he guarded John Wall and Bradley Beal in the first round, then James in the second.

“I think he has bright future,” LeBron said of Anunoby after that series. “His future is now, actually.”

By the time Anunoby was in his third season, he owned a championship ring — although he was injured for Toronto’s 2019 playoff run — and inked a four-year, $72 million extension.

“We’d go out West and he’d be guarding Nikola Jokic one night, Kawhi the next,” said Anunoby’s former Toronto coach, Nick Nurse. “Then Damian Lillard the next. All the way across the board, those guys he could defend and he’d do a really good job on all of them.”

Nurse, now the coach of the Sixers, felt that impact last week. Philadelphia’s sparkplug point guard, the 6-2 Tyrese Maxey, was held to 2 for 8 shooting when Anunoby was his primary defender as the Knicks obliterated the Sixers.

And earlier this season, while still with the Raptors, Anunoby kept 7-3 Victor Wembanyama to 4-for-11 shooting as his primary defender.

That’s over a foot of positional versatility. The Knicks are happy they don’t have to deal with that anymore.

“Playing against him,” Donte DiVincenzo said, “is not fun.

“You get that switch with that length and that athleticism, you just get ran off of it. So to have him on this side is really good.”