The rumor has made the rounds through the years that San Antonio Spurs coach Gregg Popovich, an Air Force Academy graduate who received intelligence training back in the day, was once a spy.

He seemingly put the kibosh to that talk in a 2013 Sports Illustrated profile written by Jack McCallum, while at the same time admitting that he spent part of his time in the service stationed in eastern Turkey, on the border of Iran and Syria.

Still, he told a writer named Jan Hubbard (as related by McCallum), “It wasn’t like I was James Bond.”

If he is not an international man of mystery – and let’s face it, it’s not like he would admit it if he were – it remains somewhat difficult to get a positive ID on the soon-to-be 69-year-old Popovich.

He is at once a championship-winning coach – the Spurs have taken home five NBA titles in his 22 years on the bench – and political gadfly. At once the grump who terrorizes TV sideline reporters and the charmer who can hold forth on any number of topics. At once an old-school drill sergeant and new-age innovator, forever evolving strategically and socially (recall that the Spurs are, with Sacramento, one of two NBA teams to employ a female assistant coach).

His team has likewise shifted shapes on his watch. When he started out the Spurs revolved around David Robinson and Tim Duncan. Then it was Duncan, Tony Parker and Manu Ginobili. More recently it has been Kawhi Leonard.

This year Leonard, arguably the sport’s second-best two-way player, missed the first 27 games with a quad injury, suited up for eight and then, on Sunday, was declared out indefinitely with a shoulder injury. Parker has also missed a considerable amount of time, and Danny Green has been in and out of the lineup as well.

And still the Spurs are winning. Through Sunday they were 27-14, the third-best record in the rugged Western Conference. Ginobili remains a formidable player, even at age 40. LaMarcus Aldridge has stepped up his game. Patty Mills and Pau Gasol still have something to offer. After that, though, it’s a bunch of guys named Davis Bertans and Kyle Anderson and Dejounte Murray.

But they still have Popovich, who last Tuesday won his 1,176th game to move into sole possession of fifth place on the all-time list. True to form he downplayed the accomplishment – “I don’t remember scoring any points or getting any rebounds,” he told reporters after a 100-91 victory over the Knicks in Madison Square Garden – leaving others to stand amazed.

“This league is unforgiving,” Sixers coach Brett Brown, a former Popovich lieutenant, said before his team beat the Spurs one night later. “And when I look at him and I look at the success, and the sustainability, and (he) doesn’t miss a beat – him or the program. As I’ve left it and I look in my rear-view mirror, I’m blown away at what he does and they do.”

Then again, maybe he shouldn’t be. Brown was part of Popovich’s staff for 12 years, and the first four of the Spurs’ titles. No one understands Pop – it always sounds like “Pawp” in Brown’s Down East/Down Under accent (once described by Duncan as “Bostralian”) – more completely.

And when Popovich held out Parker, Green, Leonard, Ginobili and Rudy Gay last week against the Sixers, it was nothing Brown hadn’t seen before. He recalled, in fact, ushering Duncan, Parker and Ginobili through the Orlando airport in November 2012, when Popovich elected to rest them for a nationally televised game in Miami. Then-commissioner David Stern was not amused, fining San Antonio $250,000.

“Pop can do whatever he wants,” Brown said. “He is one of those privileged coaches in a position to question government and rules. He just goes where he goes.”

And the Spurs keep chugging along.

“It’s one of those things that you learn: The system prevails,” Brown said. “Over 82 games, when you just roll into a city and roll into a city, there is a system that just moves on. Hubie Brown used to say, ‘The dogs bark and the caravan moves.’ ”

Popovich has been known to do his share of barking as well. But the buy-in by his guys always appears to be total.

“It was all me,” he deadpanned, when asked about the team’s success. “None of them had character. They were selfish people. I absolutely lobotomized all of them, turned them into a winner.”

Pause.

“At this age I can be silly, I think,” he said.

He’s always in rare form when he comes to Philadelphia, likely because the trip represents an opportunity to connect with Brown. The scowl Popovich wears for in-game interviews is replaced by a smile. The monosyllables give way to detailed explanations, as was the case when he was asked what the Spurs look for when they’re evaluating potential draftees or free agents.

No. 1 is a sense of humor. They have that, Popovich said, “They can handle criticism. They can understand what self-deprecation is. They can handle embarrassment. They can handle losses.”

And road trips, he added. Especially that.

“The other thing we look for,” he said, “are people who seemingly have gotten over themselves, or it’s more about feeling a responsibility to a teammate and to an organization. Feeling joy for the success of a colleague.”

It’s easier to read a guy on that score than you might think. Especially for Popovich, who, again, had that specialized training all those years ago.

“The guy who comes in and immediately has excuses for why he wasn’t successful in the past: ‘The coach was a jerk’ or ‘My teammates didn’t get it’ or ‘My situation was this or that,’ ” he said, “that’s a sayonara right there.”

Those guys he keeps around, he holds close, conferring with them on a weekly basis about what they are seeing and experiencing on the court.

“There’s a place for the analytics for sure,” he said, “but you can never forget about the feel and that these guys are people, and they have emotions. And if they came to work happy or sad, that falls into the decisions you make on substitutions or who’s going to play that night or not play.”

Moments later a TV guy – the kind of guy Popovich routinely eats for lunch – asked a question: Did Brown confide in him about the problems he has with his own team?

“Our conversations are our own,” he said. “Because I don’t know you. I have no idea what you might do with the information. You look a little shaky to me.”

Smiling the whole time.

“You can give it to me now, and we’ll chat afterward,” TV guy said, “and get to know each other.”

“No, I’m not that interested in knowing you,” Popovich said, still smiling.

Laughs from the rest of the media pack.

“I’m just joking,” he told the guy.

And it’s possible he was. But you never know, because he certainly always leaves you guessing.