HOUSTON -- When a pitcher in his late 30s begins to struggle, the reasons can be difficult to deduce. Is it the type of slump all players go through at points in their careers? Is it the result of steady decline? A blip that will pass or the beginning of the end?

Faced with these whispered questions Monday evening at Minute Maid Park, six days after one of the worst starts of his career, Max Scherzer gave the most emphatic answer he could. Prior to Monday, Scherzer had not pitched into the eighth inning of a game since joining the Mets. In an 11-1 drubbing of the Astros that also included offensive breakouts for Francisco Lindor and Daniel Vogelbach, Scherzer completed eight strong ones to quiet talk of his issues.

“It’s our job to go out there and pitch deep,” Scherzer said. “Frankly, I haven’t been doing that the past couple of starts.”

So Scherzer set about changing that trend against a team that, despite a relative downturn, remains one of the league’s noteworthy offenses. The most impactful piece of Scherzer’s renaissance was his slider, which he often describes as his bread-and-butter pitch. It was the slider that had betrayed Scherzer during his last start, hanging over the heart of the strike zone during crucial moments. Against the Yankees, Scherzer threw 17 sliders and generated just one whiff.

Six days later, he threw 31 of them with seven swings and misses.

“He executed his slider a lot better,” catcher Francisco Alvarez said through an interpreter. “A lot, lot better.”

For Scherzer, the fix was relatively simple. Earlier this month, he tweaked the arm action on his changeup, hoping to make that pitch more consistent. When the adjustment worked, Scherzer tried to apply the same fix to his slider. That had the opposite effect, prompting him to revert to his old mechanics on both pitches.

Just like that, the old slider was back and plain to see: on consecutive swinging strikes against Jose Altuve to record his first out of the night; on back-to-back strikeouts of José Abreu and Yainer Diaz in the second inning; and so on and so forth. Although Scherzer allowed his only run on a slider when Diaz homered with one out in the seventh, he wasn’t displeased with the quality of that pitch. He remained confident in it. Two batters later, Scherzer followed a sharp inside slider to Jeremy Peña with a 95 mph fastball on the outside corner to freeze him.

“He's not throwing quite as hard as I’ve seen him, but he always had a good slider,” said Astros manager Dusty Baker, who managed Scherzer for two years in Washington. “It was the slider that set up everything else tonight.”

Mostly, Scherzer was glad to anchor a win for a team that had lost seven consecutive games against the Astros, not to mention 11 of 14 overall. Other Mets played prominent roles -- Lindor, for example, who hit a three-run homer in the third inning and a two-run double in the ninth, and Vogelbach, whose contributions included a solo homer and a two-run single. But it was the starting pitcher who remained in the thick of things all evening.

When Scherzer reentered the dugout after the eighth inning, having induced a double-play ball to complete his night on just 91 pitches, he began bantering with several of his teammates. The heaviness that trailed him following his last start seemed to have vanished.

Scherzer is not, manager Buck Showalter said afterward, “some ogre that you can’t be around or talk to” following poor starts. But he is a harsh self-critic, constantly searching for fixes. Those personality traits applied when he broke into the league at age 23. They remained true when he earned his first Cy Young Award at age 28, and when he won a World Series at age 34.

Now, a month shy of his 39th birthday, Scherzer is as committed to improving as ever. He’s clearly still capable of it, as well.

“We had a real need to get deep into that game,” Showalter said. “For him to go eight innings, that was pretty special in a lot of ways.”