Tim Duncan walked out of the visitor’s locker room at Staples Center and stopped to chat with Chris Paul after the San Antonio Spurs completed their four-game annihilation of the Los Angeles Clippers last week. But the conversation kept getting interrupted so that Duncan could joke around with Paul’s 2-year-old son, Chris.

Duncan asked the younger Paul to show him his muscles and the kid flexed proudly. He then laughed as Chris Jr. answered questions from his father about what number Duncan wears (“21”) and what college he plans to attend (“Wake Forest”).

The playful ease with which Duncan interacted with the toddler may come as a surprise to those who consider him to be the most dull superstar to lace them up. But in many ways, Duncan is having the same effectiveness playing basketball this season against a new generation of big men who were barely in elementary school when he first came into the league.

Duncan, 36, came back with something to prove after a season in which the Spurs were eliminated from the first round by Memphis and he recorded the worst statistical season of his career. It has helped San Antonio get back to the Western Conference Finals for the first time in four years.

“A lot of people messed up saying he was old last year,” Spurs reserve Stephen Jackson said about Duncan, as San Antonio prepares to host the Oklahoma City Thunder in Game 1 on Sunday at AT&T Center. “He worked his butt off this summer to play the way he’s playing now.”

Duncan changed his offseason program to get in better shape and take some pressure off his achy knees. The result has been a player with much more lift and explosion, which he displayed when he rejected a dunk attempt by the Clippers’ 23-year-old high-flying all-star forward Blake Griffin in the conference semifinals — though Duncan was modest in his description of the play.

“I think I got him on the way up. That’s the only chance I have,” Duncan said with a laugh.

Duncan certainly looks as if he can effectively play a few more years at a high level. How much longer is anyone’s guess. “I don’t have that kind of crystal ball,” Spurs Coach Gregg Popovich said.

Popovich can’t be expected to know how much longer Duncan can lead professional sports’ most consistently successful franchise of the past 15 years when he surely had no idea that their union would yield so many accolades for both of them. Since the Spurs lucked into landing Duncan with the No. 1 pick in 1997, no player-coach tandem has more playoff victories (184), more regular season wins (792) or a better winning percentage (.713). And, they are now eight wins from claiming their fifth NBA championship together.

“I’m incredibly fortunate,” said Duncan, who won the first of back-to-back most valuable player awards 10 years ago. “I understand the situation I’m in. It doesn’t happen for a lot of people. The organization, the players, the coach. In every respect, I’ve been blessed. I understand it everyday and I appreciate it everyday.”

Popovich won coach of the year honors for the second time, but he has always deflected praise in the direction of Duncan, whom he credits for the incredible run. “I’ve got one hand hanging on his coat tail,” Popovich said. “He just keeps dragging me around wherever he goes. Every time I walk around the house, about once a month, I tell my wife, ‘Say, ‘Thank you, Tim.’ And I’m serious.”

Former Spur and TNT NBA analyst Steve Kerr described the union of the white-haired, Midwestern-rooted Air Force grad who once desired to work for the CIA and the U.S. Virgin Islands native who once desired to be a competitive swimmer as the “perfect fit.” The reason the relationship has worked so well for so long, Kerr said, is because of Popovich’s gregarious but commanding presence and the “mild-mannered” Duncan’s willingness to let Popovich coach him.

“It’s an incredible dynamic in San Antonio that goes back to Tim and David [Robinson], earlier,” Kerr said. “I remember several halftime speeches, or post game, where Pop is coming out of his shoes, lighting into those guys. They accepted it and that’s a tough thing to find.”

Spurs vice president of basketball operations Danny Ferry won a title with the team in 2003 and said the success is rooted in mutual trust. “It was built early on, respected and protected, throughout their time together,” Ferry said. “Whatever Pop was doing with Tim, I think Tim knew was best for him and the team.”

In Duncan’s time in San Antonio, the Spurs have transitioned from being a methodical, veteran-laden halfcourt team built around the inside talents of Robinson and Duncan to a more wide-open offensive unit that relies on the dribble penetration of Tony Parker and Manu Ginobili and younger, athletic three-point shooters.

The current incarnation was necessitated by the Spurs’ recent postseason shortcomings. They haven’t won a title since 2006-07 and lost in the first round for the second time with Duncan in uniform last season.

But Duncan never lost faith in the ability of Popovich and Spurs general manager R.C. Buford to make the team relevant again.

“This is my first team,” Duncan said. “I don’t know about what happens with everybody else. We’ve been blessed to be contenders year in and year out and put good teams together. For the most part, going into a postseason, we’ve felt that we’ve had a chance to make a run at it.”

Duncan also did his part to repay their commitment this season, as he recorded a bounce-back season of sorts, though he failed to make the all-NBA team for the second year in a row. His per-36 minute scoring (19.7) and rebounding (11.5) numbers were on par with his career averages (20.6 and 11.5).

Jackson is back with the Spurs after bouncing around five different teams the past nine seasons, but said Duncan remains unchanged, noting how he continues to dress like a teenager in the 1990s — extra baggy jeans and untucked button-down plaid shirts.

“Same guy, still dresses the same, still approaches the game the same,” Jackson said. “Still wants to win.”

That consistency has kept Duncan from losing focus on what matters to him — winning for as long as he can. “It’s essential,” he said. “I think, trying to stay cool and collected, when things are going all different directions around you, you keep that even keel and you’re not affected by the goods and bads as much. It’s a great quality to have.”