PHOENIX -- Jason Kubel is a quiet guy making some serious noise with his bat in his first season with the Arizona Diamondbacks.

Never was he louder than Saturday night when he became the seventh player in Diamondbacks history to homer three times in a game, driving in six runs as Arizona dominated the Houston Astros for the second straight game, 12-3.

In a home park that loves a left-handed hitter, Kubel came out swinging when he came from Minnesota as a free agent and has emerged as one of the most effective sluggers in the National League.

"I put some good swings on some balls, some balls up," he said. "The balls I was missing yesterday, I wasn't missing tonight. I'm just happy with how it turned out. It was a fun win for us."

Kubel hit a two-run home run in the first inning and a three-run shot in the fourth off starter Dallas Keuchel (1-2). He added a solo homer off reliever Enerio Del Rosario in the sixth. Left-handed pitchers such as Keuchel are supposed to have an advantage against left-handed hitters. Kubel's power display defied that conventional wisdom.

"You don't see many games like that," Arizona manager Kirk Gibson said. "He just loves the fastball and was seeing it good. The second one was pretty impressive. It looked like it was in on him as well. He gets the bat there really quick, to all fields. He's got a very short stroke and he gets the barrel to the ball."

With the first three-homer game of his career, Kubel leads the NL with 70 RBIs.

"I'm hoping to do more. We've got a good amount of baseball left," he said. "As long as guys keep getting on base for me, then hopefully I can keep going. I definitely like the park a lot. I like the team. It's great. There's great chemistry here. I definitely like what they did last year and I think we've still got it in us this year."

Wade Miley (11-5) gave up a run and four hits in seven innings, striking out a career-high nine while setting a franchise rookie record for victories.

The Astros lost their fifth straight and 18th in 20 games.

Kubel, signed as a free agent in the offseason, is one of six players to hit three home runs in a game this season. That includes Josh Hamilton, who hit four. Kubel has 20 home runs, including a two-homer game Thursday in Cincinnati.

Willie Bloomquist went 3 for 4 with three RBIs for the Diamondbacks. Aaron Hill singled in the fifth to extend his hitting streak to 12 games.

The Diamondbacks, on the opening weekend of a 10-game homestand, have outscored the Astros 25-11 in the first two games of the series.

After walking six in Friday night's 13-8 loss, Houston walked eight on Saturday. Of those 14, 10 scored, four on Saturday.

"My command today down and away with the sinker was poor, to say the least," Keuchel said. "I made some mistakes over the plate with runners on and that hurt me."

Keuchel, called up from Triple-A Oklahoma City for the start after J.A. Happ was sent to Toronto on Thursday in a 10-player trade, allowed seven runs and seven hits and walked four in 3 1/3 innings.

Kubel gave Miley a quick lead in the first. Hill walked with one out, then the Arizona slugger hit Keuchel's 2-2 pitch just over the fence in left field, a two-run opposite-field shot,

The Astros cut it to 2-1 in the fourth. Justin Maxwell led off with a ground-rule double and J.D. Martinez walked. Miley got Ben Francisco to pop out, then fanned Matt Downs, but Chris Johnson's single brought Maxwell home. Chris Snyder walked to load the bases before Keuchel grounded out to end the inning.

Kubel's first-pitch homer highlighted Arizona's five-run fourth inning that made it 7-1. Arizona added two in the fifth on Bloomquist's single that brought home Chris Young and Ryan Roberts, both of whom had walked. Kubel hit a 2-2 pitch over the fence in left-center leading off the sixth to make it 10-1. The crowd of 35,665 stood and cheered until Kubel came out and tipped his cap in appreciation.

Third base umpire Kerwin Danley left in the middle of the sixth inning to attend to an unspecified personal matter.

Game notes
Takashi Saito, activated from the DL earlier Saturday, relieved Miley in the eighth and became the first Japanese player to play for the Diamondbacks in franchise history. ... Josh Collmenter (2011), Oscar Villarreal (2003) and Brandon Webb (2003) also won 10 games as Arizona rookies. ... The Astros named RHP Francisco Cordero closer after RHP Brett Myers was traded to the Chicago White Sox earlier Saturday for two minor league prospects. ... RHP Collmenter (1-2, 3.90 ERA), returning to the rotation after RHP Trevor Bauer went back to the minors, goes in Sunday's series finale for Arizona against Houston RHP Jordan Lyles (2-6, 5.29). ... Houston has not won a series since taking two of three from Cleveland July 22-24. The Astros' last road series win was June 8-10 against the White Sox in Chicago. ... Arizona has won 16 of 20 against Houston dating to Aug. 23, 2009.