It would be easy to look at Monday night’s opening game of the Western Conference semifinal between the Rockets and Spurs — a 126-99 thrashing by Houston in San Antonio — as an aberration, and write it off as a bad night at the office for the Spurs’ machine.

In many ways that is true: San Antonio shot 36.9 percent against a porous Houston defense, and the Rockets went 22-for-50 from three-point range. A swing like that won’t likely happen when they meet again Wednesday night for Game 2.

But dismissing everything that went wrong for the Spurs Monday night as nothing more than a correctable series of errors would be a major mistake. Houston exposed several key flaws in San Antonio’s rotation — flaws that were evident before the series began. The question, though, is whether the Spurs’ famously stubborn coach, Gregg Popovich, will make the necessary changes before it’s too late.

Popovich has earned his reputation as one of the best coaches in the history of the sport, presiding over 20 consecutive 50-win seasons (or, in the case of the 50-game season in 1999, a season well ahead of a 50-win pace), winning five championships and reaching six NBA Finals. But Popovich has never been known as a coach who makes drastic changes during playoff runs. If anything, when things start to go south for San Antonio in a playoff series, they tend to remain that way.

Take last season against the Oklahoma City Thunder, for instance. By dominating San Antonio inside with multi-big lineups featuring Steven Adams, Serge Ibaka and Enes Kanter, the series was crying out for Popovich to deploy Kawhi Leonard at power forward and play small. Popovich finally made this switch … in the second half of Game 6, after the Spurs had fallen hopelessly behind in what turned out to be the final game of their season.

That example is instructive when examining what took place Monday night. As in that series, San Antonio had serious lineup flaws. In the opening minutes of the game, as the Spurs found themselves being blown out, Popovich twice called timeouts to berate his starting center, David Lee, for defensive mistakes defending Houston’s lethal pick-and-roll offense.

Here’s the problem: Blaming Lee — who has worked to improve his defense, but is subpar at best — for defensive miscues is like giving a child a cookie and them blaming him for eating it. It simply isn’t fair, particularly when Lee is being put into the blender that is trying to shut down Harden, who had 20 points and 14 assists in 31 minutes, expertly running Mike D’Antoni’s vaunted offensive system.

This was only the beginning of San Antonio’s problems. Danny Green, an excellent perimeter defender, got yanked after just a couple of minutes after being screamed at by Popovich for a defensive miscue, and played just 21 minutes. This cannot happen. If Green is going to guard Houston’s many deadly perimeter players, he has to be playing close to 40 minutes a game, so he and Leonard can team up to attempt to limit the Rockets’ offense. With Green on the bench, that left the Spurs relying heavily on Tony Parker, Manu Ginóbili and Patty Mills — all of whom are significant defensive downgrades from Green.

Meanwhile, Popovich insisted on playing two big men together through large portions of the game. That meant Lee, Pau Gasol and LaMarcus Aldridge were all in space trying to guard defenders on the perimeter, which helped free up the Rockets for one open look after another. This was particularly true for Ryan Anderson, who had 14 points on 4-for-10 shooting from behind the arc, and who created so much spacing with his ability to shoot from deep that San Antonio’s defense couldn’t handle it.

The fact Leonard played just two minutes as a small-ball power forward — against a team that spends so much time playing small to begin with — was something that seemed like an obvious fix. So, too, was playing Dewayne Dedmon, easily San Antonio’s best defensive big. Instead, Dedmon was glued to the bench until long after the game was decided (and then he came in and scored six points in seven minutes before getting ejected for picking up a pair of technicals).

What’s clear is that, even with San Antonio’s structural defensive issues (and particularly against Houston, which has the shooting and athleticism to exploit the usual suspects in the Spurs’ rotation), Popovich can adjust going into Game 2 and beyond to give his team a chance to regain its footing.

Doing so, however, would go against Popovich’s usual nature, which is to trust in what his team does and believe things will properly balance out with better execution, as he hinted Monday.

“I don’t think we executed in a very wise manner,” Popovich said. “We disobeyed a lot of basic basketball rules that they can take advantage of.”

As usual, Popovich is correct. But that isn’t the only issue plaguing the Spurs. And if he isn’t willing to address those other issues, an already difficult task to climb back into this series after Monday’s blowout loss will be that much harder.