ANAHEIM -- With the way Astros starting pitcher Framber Valdez threw the ball so erratically in the bullpen in his pregame warmup on Monday night, veteran catcher Martín Maldonado couldn’t help but think the worst. Valdez threw maybe five strikes in his 30-pitch warmup, Maldonado said, and then he spiked his first warmup pitch on the mound into the Angel Stadium grass.

“I said, ‘Wow, this is going to be a bad day,’” he said.

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Valdez quickly refocused and spotted three consecutive sinkers in the zone to strike out Brandon Marsh looking, setting the tone for one of the lefty’s best outings of the season. Valdez threw seven scoreless innings, striking out six batters and allowing six singles and three walks, to lead the Astros to a 10-0 win over the Angels in the series opener.

“Amazing,” Maldonado said. “That’s a guy that’s been doing it all year. You guys have been here watching him, for the most part. He keeps getting better and better every day.”

The Astros (89-61) reduced their magic number to clinch their fourth American League West title in five seasons to six with their win and the A’s loss to the Mariners. Houston leads the division by seven games over Oakland and eight over Seattle.

“If you just keep winning, that magic number will no longer be magic,” Astros manager Dusty Baker said.

Valdez was pitching for the first time since throwing five innings to beat the Angels in Houston on Sept. 10, when he gave up four earned runs on six hits (two homers) and five walks with six strikeouts. He had his start pushed back after cutting his left index finger on the outfield wall while shagging fly balls.

“My finger recovered quickly just like I wanted it to, and it wasn’t bothering me at all,” Valdez said. “I was able to execute my pitches like I wanted to. Thank God I was able to recuperate.”

Valdez (11-5) threw 60 of 98 pitches for strikes, relying mostly on his sinker-curveball combination. He threw 67 sinkers, which produced 31 swings (four whiffs). Valdez, who entered the game with a Major League-best 69.2 percent ground-ball rate (minimum 100 innings), recorded 12 ground-ball outs and two flyouts.

“What impressed me was the strike-zone command early in the game,” Baker said. “He had a very low pitch count up until the sixth inning and then he ran into trouble in that inning.”

The Angels put runners on first and second in the sixth and then loaded the bases in the seventh with two outs. Valdez got David Fletcher to hit a grounder to shortstop Carlos Correa, who made a great play to throw him out at first and preserve the shutout. The Astros responded with a four-run eighth, capped by a three-run homer by Maldonado.

“I think he’s the best shortstop I’ve played with,” Maldonado said.

Maldonado has been impressed with Valdez’s development from a pitcher who posted 5.6 walks per nine innings from 2018-19 to one of the top lefties in the game last year. That's true even though his walk numbers have risen from 2.04 walks per nine innings last year to 3.88 this year (53 in 123 innings).

“I’m so happy to see this development throughout his career,” Maldonado said. “You might remember the Framber of 2018 -- the one who couldn't throw a strike. I would say Houston did a pretty good job of believing in the kid. Especially when he walked that many guys back in the day, people don’t get a chance, especially with the staff we had back then. The way he’s come along is really impressive.”

Valdez benefitted from one of Houston’s biggest offensive showings of the season, which began with a Jose Siri leadoff homer and was capped by a grand slam by Marwin Gonzalez in the ninth. Correa’s four hits led the 17-hit attack, and relievers Brooks Raley and Seth Martinez (MLB debut) polished off Houston’s eighth shutout win of the season.