Four championships and nearly 15 years later, Duncan and the San Antonio Spurs are still around, still relevant, still contenders as they arrive at Staples Center on Monday night to play the Clippers.
The NBA's steadiest franchise has sustained its excellence through a few singular characteristics.
"Great owner, great management, great coaches, great players," said Van Gundy, the former New York Knicks coach whose team the Spurs vanquished in the 1999 Finals, "and no one looking for the credit."
The Spurs' selflessness can be seen in the way they play, always making the extra pass and looking for each other, the team above all else. It can be seen in the way they construct their roster, with a premium on high-character players and possible distractions such as Stephen Jackson cast aside.
It can also be seen in the way Gregg Popovich coaches his team, removing stars late in games if he thinks it gives the Spurs the best chance to win. That doesn't always work out, as everyone saw in Game 6 of the Finals in June.
Wanting his best perimeter defenders on the court with the Miami Heat needing three-pointers trailing by five points in the final 28.2 seconds, Popovich removed his best rebounder in Duncan.
Two Miami rebounds and a pair of three-pointers later (along with two missed San Antonio free throws), the Heat forced overtime and eventually wilted the Spurs in the game and the series.
It was a meltdown that left the Spurs dripping with its sticky, messy remnants all summer long.
Super sub Manu Ginobili reportedly had to ask waiters and hotel staff to stop bringing up the Finals while vacationing in the Caribbean. Shooting guard Danny Green told reporters he saw a replay of the Finals on his father's living room television and kept walking.
And then there's Popovich, who seemed most devastated by it all. The coach told San Antonio Express-News columnist Buck Harvey before training camp that he had been feeling "quite lugubrious."
For those of us who didn't soak up English at an esteemed liberal arts college such as Pomona-Pitzer, where Popovich spent nearly a decade as coach (while also serving as an associate professor at Pomona), that means "mournful, dismal or gloomy."
The Spurs (19-4) haven't had much to mope about since the season started, rolling up 11 consecutive victories at one point while again establishing themselves among the Western Conference's elite teams.
Duncan has come around after a slow start, averaging 15.5 points and 10.2 rebounds while shooting 54.6% over his last 11 games. Point guard Tony Parker has maintained the steady play that helped lead his French team to its first EuroBasket championship over the summer, and Ginobili has supplied his usual infusion of assists and energy off the bench.
Popovich's foreign legion may even have found its newest foot soldier in Aron Baynes, the undrafted second-year center from Australia who had 14 points and six rebounds during a recent victory over the Toronto Raptors.
Duncan has become a symbol of longevity as he approaches his 38th birthday in April, but he's not a sight gag like that Rocky XXXVIII poster in the background of the gift shop scene in "Airplane II."
The power forward-center has rolled up 24,073 points (fifth among active players) and 13,403 rebounds (second) in 1,201 games without any appreciable decline over 17 seasons. He's averaging more points and almost as many rebounds as he did three seasons ago.
Of course, Duncan won't be around forever, even if it seems that way. Succession plans will eventually need to be made.
"They have to keep replenishing their talent pool as Duncan and then Ginobili and Parker age," Van Gundy said, "but never bet against great, talented people who have a common goal and are willing and able to suppress their own ego for the betterment of the group. I have such great admiration for the way they go about their business."
They're still open for championship business after all these years, the moments not fleeting as Duncan once feared.