Duncan announced his retirement on Monday, but wasn't present for Tuesday's news conference.
"It's not a show of humility in any sense or form. People who grew up with me know me," Popovich explained. "I would not be standing here if it wasn't for Tim Duncan. I'd be in the Budweiser League someplace in America, fat and still trying to play basketball or coach basketball. But he's why I'm standing. He's made livings for hundreds of us, staff and coaches, over the years and never said a word, just came to work every day. Came early, stayed late, was there for every single person, from the top of the roster to the bottom of the roster, because that's who he was, in all those respects."
Sources told ESPN's Marc Stein that the Spurs officially waived Duncan on Monday for salary-cap reasons. While the move was a mere formality, the club needed to do it to "waive and stretch" Duncan's $6.4 million salary for the 2016-17 season so that it's spread out over three seasons instead of one, which lessens the cap hit the team will take.
Duncan exercised his player option for the upcoming season before the June 29 deadline, which means he'll receive his full salary for the upcoming season despite retiring. Consider it a parting gift for Duncan, who gave so much for the NBA, the city of San Antonio and the Spurs organization.
"He's irreplaceable. It can't happen," Popovich said. "We're all unique. I guess each one of us is unique. But he's been so important to so many people, it's just mind boggling. To think that he's going to be gone makes it really difficult to imagine walking into practice, going to a game, getting on the bus, taking him a piece of carrot cake -- whatever it might be.
"You don't see Timmy beating his chest as if he was the first human being to dunk the basketball, as a lot of people do these days. He's not pointing to the sky. He's not glamming to the cameras. He just plays, and we've seen it for so long it's become almost mundane. But it's so special that it has to be remembered."
Popovich said Duncan is "too smart" to try his hand at coaching in retirement, but he plans to reach out to the former Spur to keep him involved in some capacity.
"I don't think we're going to see Timmy going up and down the sidelines much," Popovich said. "But I have a notion he will at least listen to being involved, somehow or other, maybe even on a part-time basis. I'm certainly going to hit with everything I have to keep him around here as long as I possibly can because he means that much to everyone in the organization."