SAN ANTONIO -- Discomfort contorted Gregg Popovich's face as he pondered a defensive demise nobody wanted to concede.
With the San Antonio Spurs mired in a three-game skid at the time, and mere minutes before the Feb. 27 start of a league-best nine-game winning streak, Popovich seemed to have given up hope for the return of a defensive foundation that had buttressed the franchise for more than two decades.
"We used to call it 'stops on demand,'" he said, "where at certain points in the game, if you needed to get [defensive] stops, you could always depend on it. We haven't acquired that identity yet."
But 19 days after Popovich lamented potentially losing it, the Spurs leaned on a suffocating defense Monday night to best the defending champion Golden State Warriors 111-105, while limiting the visitors well below their 117.7-point scoring average.
Surging toward a 22nd consecutive postseason appearance, the Spurs have transformed from perhaps the worst defensive unit in Popovich's 23 years at the helm to one of the best in the league.
"I'm just seeing an enigma that we're trying to figure out," Popovich had explained when San Antonio's winning streak first started. "We were horrible a big part of the year, the first third or quarter or whatever you want to call it. Then we had that 10- [or] 12-game stretch where we were like first or second in every defensive category. And then we went back to 28th and 29th for a stretch."
The Spurs ranked No. 21 in defensive efficiency before embarking on their annual rodeo trip Feb. 3, only to fall back even further in the NBA rankings. During their worst-ever rodeo trip (they finished with a 1-7 record), the Spurs bottomed out by yielding 122.1 points per 100 possessions, worst in the league during that stretch of the calendar.
It was not familiar territory for a Spurs team that hasn't ranked outside of the top five in defensive efficiency since 2011-2012.
But it appears a real turnaround is at hand. The Spurs are second in defensive efficiency at 103.1 points allowed per 100 possessions since Feb. 26.
The Spurs held Stephen Curry and Klay Thompson to a combined 4-of-22 in the first half Monday night, which registers as the duo's worst combined field goal percentage in a first half in their careers (minimum 15 shots), according to ESPN Stats & Information research.
"To be the last team standing, you've got to be near the top in both [offensive and defensive] categories," Popovich said. "You don't have to be at the top in both, but being relatively close is important. That's been the history."
In each of San Antonio's five championship seasons, the Spurs finished in the top three in defensive rating and 11th or better in offensive rating. Even last season, the Spurs ranked third in defensive rating despite two-time NBA Defensive Player of the Year Kawhi Leonard participating in just nine games.
Since the 1998-1999 season, the Spurs are the only team to rank in the top five in both defensive rating (first) and offensive rating (third) overall for that 20-year interval.
They're still 20th in defensive efficiency overall this season, but the team is encouraged by the recent stretch of strong play.
"I think we're on the corner. We're still turning it," Spurs guard Patty Mills said recently. "These are all great examples of us and the way that we need to play. But for us to have the games that we've had defensively [recently] is a huge confidence boost for us. We just need to lock in that feeling of how we play and keep it rolling.
"We can show that we can play the way that we need to play to be in the playoffs -- and make a run in the playoffs."
The Spurs are No. 5 in the West, just 1.5 games behind Portland.
San Antonio's defensive slide coincided with the absence of point guard Derrick White, a first-year starter and a revelation on defense. The 24-year-old missed six of San Antonio's eight games on the rodeo trip. The Spurs captured victories in eight of 11 outings since the return of White, who ranked fifth among guards in defended field goal attempts per game with a minimum 50 games played. And of the 30 guards to defend at least 10 shots per game, White ranks fourth in opponent field goal percentage allowed, according to NBA advanced stats.
But the cracks in the defensive foundation predated White's most recent injury setback, which kept him out of six games.
Over the summer, the Spurs lost two of their top wing defenders from last season in Kyle Anderson, who signed a free-agent deal with the Memphis Grizzlies, and Danny Green, who departed for the Toronto Raptors as part of a trade that Leonard demanded. Future Hall of Famer Manu Ginobili retired, and point guard Tony Parker opted to play his 18th season for the Charlotte Hornets.
Starting point guard Dejounte Murray, who earned recognition last season as a member of the NBA's All-Defensive team, tore his right ACL against the Houston Rockets during the preseason. Murray's injury paved the way for White to become the starter.
In all, the Spurs have nine players on the current roster who weren't a part of the team last season. On top of that, they're playing with essentially four new starters. Mills, a 10-year veteran, is now the longest-tenured member of the team at eight seasons with the Spurs.
Popovich often refers to the "corporate knowledge" that for years was passed along to younger players from vets such as Parker, Ginobili and the retired Tim Duncan.
For a while this season, the Spurs wondered whether it was gone.
In perhaps the most significant test since the start of its winning streak, San Antonio corralled Golden State's top three perimeter threats -- Kevin Durant, Curry and Thompson -- and held them to a combined 23-of-61 (37.7 percent) from the floor for 63 points on Monday.
"I think more than anything, probably part of the answer is we haven't been together long enough either in the system or the players with each other to form habits and be consistent in those areas," Popovich said. "So, we'll be really good for a while, and then we'll be really poor. It hasn't become a habit yet. The culture hasn't sunk in definitively enough to have that consistency, and we've been used to that for a long time.
"With a group of new guys in a new system, it's gone slowly. We've been in valleys, up and down defensively. That consistency has never taken root."
San Antonio's defensive efficiency (110.7), opponent field goal percentage (46.4), opponent points per game in the paint (46.7) and opponent assist to turnover ratio (2.01) for the season all rank as the worst in the Popovich era.
But that wasn't the defense Warriors coach Steve Kerr saw in Monday's contest.
"They play hard," Kerr said. "They have been a very good defensive team down this last couple of weeks. Much improved defensively, they are hot right now. I was frustrated a little bit, our guys were a little frustrated. But we've got to bounce back."
Aside from White, another boost for the defense comes from 7-foot center Jakob Poeltl, who has helped All-Star LaMarcus Aldridge to bolster protection against shots inside the arc. After struggling earlier in the season at adjusting to his role in San Antonio's system, Poeltl is averaging 2.1 blocks since Feb. 26. Poeltl tied a career high with five blocks in each of the previous two games headed into Monday's clash with the Warriors, joining elite company in Duncan, David Robinson and Antoine Carr as the only Spurs to have totaled five or more blocks in back-to-back outings.
Meanwhile, with White matching up against the opponent's top perimeter threat on most nights, San Antonio's defense has been 4.0 points per 100 possessions better with him on the floor. As of games through Monday night, the 6-foot-4 White ranks No. 1 in the NBA among guards in contested shots per game (9.5), and he averages 1.6 blocks per game since Feb. 26.
"It's a combination of Jakob -- he takes up a lot of space, he's pretty mobile, he allows [Aldridge] to do some other things out there," Popovich said. "But Derrick White is a big part of that also. He sets the tone for us out on the perimeter, and Jakob guards pick-and-roll really well. He's got good mobility, and he moves around on the court where he can cover a little bit more ground near the rim. So it helps us."
That, in turn, aided San Antonio on its roll to a ninth consecutive victory -- and an 11th straight win at home.
"It was the defense," Spurs guard DeMar DeRozan said after finishing with a game-high 26 points. "We didn't cave in. We kept them to 105 points."
Popovich offered his take.
"We worked hard. We made a lot of mistakes against the best team in basketball, probably," the coach said. "You know, they're the defending NBA champs, and they move and cut better than anybody in the world. So, it was a great classroom, so to speak, to be able to try to guard that all night long. The effort was there for 48 minutes, and we learned a lot, hopefully. So, that's a good thing."