ESPN Stats & Info put the achievement into historical perspective:
Former Spurs forward Sean Elliott discussed Popovich's legacy, via the San Antonio Express-News' Mike Monroe:
I’d say it’s being the no-nonsense winner who changed the culture and the way that things were done here for a long, long time and changed them for the better. He’s a model of perseverance and leadership and consistency and integrity, and those are just among the superlatives you can use.
Interestingly enough, when the man now affectionately known as Pop was hired, it was seen as "one of the most controversial personnel moves in Spurs history."
After San Antonio, which had won at least 55 games in the three previous seasons, got off to a 3-15 injury-riddled start in 1996-97, Popovich, who was the team's general manager and vice president of basketball operations at the time, fired Bob Hill and named himself head coach.
He didn't fare much better, as the Spurs, playing all but six games without David Robinson, finished 17-47 under Popovich. But that netted them the No. 1 overall pick, who turned out to be a quiet kid from Wake Forest by the name of Tim Duncan.
In the next 17 seasons, Pop's Spurs won at least 50 games 16 times—with the only exception being a 37-13 record during the strike-shortened 1998-99 campaign, which resulted in his first NBA championship. A brilliant basketball mind and perhaps even better teacher, he has gone on to win five total titles and three Coach of the Year awards, establishing a near-unprecedented run of success.
Duncan, Manu Ginobili and Tony Parker, who have remained a constant for more than a decade, showed their appreciation for Popovich:
It doesn't hurt to have such a dedicated core for so long, but plenty of coaches have done far less with more talent. Pop, who has stirred up controversy for resting his stars from time to time, has shown an ability to develop young players and get the most out of everyone on his roster. He gets players to buy in, and his system works at the same dangerously efficient level no matter who's on the court.
Continuing to live up to those lofty standards will be difficult once Duncan, Parker and Ginobili are gone (assuming they aren't robots), but as long as Popovich is on the bench, the Spurs will continue to do what they have for the better part of two decades.