"I was moving fastballs around a little more as the game got going. That's the fun part of starting," said Triggs, who issued no walks and gave up only five hits. "You may lean on one pitch earlier, then go to some others later."
While Triggs, a former reliever, was energized in making his fifth start of the season (11th of his career), it wasn't much fun for the Astros, who didn't score until Triggs exited.
Triggs (4-1) is tied for the American League lead in wins, and Saturday marked his fourth start this year without yielding an earned run.
His command got sharper as the game progressed.
"To pitch as well as he did, go through the lineup three times, seven innings of work, that's pretty good," A's manager Bob Melvin said. "He had the one off outing, and every outing since then has been pretty spotless."
In his previous start, Triggs took the loss in an 11-1 thumping to the Mariners last Sunday. In that game, he gave up six runs over 4 2/3 innings. His cutter/slider wasn't sharp against Seattle.
Everything was working against the Astros on Saturday for Triggs, whose previous career high was eight strikeouts on Aug. 28, 2016, at St. Louis. Triggs was making his third career appearance against the Astros, but his first as a starter.
"The arm angle when he's throwing strikes is difficult," Melvin said. "And you look at his numbers against lefties this year. His numbers against lefties are as good as any right-handed starter in the league, which is one area of concern coming in based on his body of work over his career.
"But the ball's moving, and from that arm angle when he's throwing 91 [mph], it looks like 94 for a hitter, and he had a sharp breaking ball."
Triggs has not allowed more than one hit to left-handed batters in any of his five starts. They are hitting .087 (4-for-45) against him this season. Last year, lefties batted .277.
"When you command pitches, you're going to get guys out," Triggs said.
Triggs said it's a thrill to set a career high in strikeouts, even though he wasn't fully aware of the situation.
"It was fun. I was unaware, but I knew we were getting a few more swings and misses than we had in the few outings earlier," Triggs said. "Yeah, it was exciting. But at the end of the game, my focus was getting as deep as I could and keeping them off the board."
Richard Dean is a contributor to MLB.com based in Houston and covered the A's on Saturday.