Miller racked up five RBIs on his two bombs and Kyle Seager and Justin Smoak added home runs of their own as the Mariners have now homered in a club-record 23 straight games, tying them for the sixth-longest streak in the Majors since 1916. The Rangers hold the record of 27 consecutive games with a homer, set in 2002.
"Everybody is just piecing good at-bats together, honestly, not trying to do too much," said Miller, who went 3-for-5 to raise his average to .273 after three weeks in the Majors. "I don't know why, but hitting is contagious. Guys have good at-bats, even if they don't get a hit necessarily and they hit a ball hard or make a loud out, it just sets the tone."
The Mariners' tone has been trending positively of late, winning nine of their last 14 games to improve to 44-52, while Houston fell to 33-62 in its first season in the American League West.
Miller's second-deck blast in the sixth inning was the first of his Major League career and he followed that with a three-run pop just over the right-field fence in his next at-bat in the eighth.
What did it feel like to hit two homers in one night after waiting 72 at-bats for his first?
"I don't even know," he said. "I was obviously pumped up for the first one. I was just trying to hit the ball well. And then just trying to have another good at-bat and I was able to get another one. It was fun. They kept battling back, all those runs, we needed to keep going."
Miller also made an outstanding defensive play in the fourth with a backhand stop and glove flip to second baseman Nick Franklin, who barehanded the toss and fired to first for a key double play. But, of course, the focus was on the home runs afterward.
"He has power," said manager Eric Wedge. "He has considerable power. Just talking the ball off the bat, the way it jumps. He's going to be a hitter first, but he'll hit a few home runs."
Seager's 16th homer of the year extended his hitting streak to 15 games, the longest current run in the Majors, and Smoak finished things off with his ninth homer of the year for a welcome insurance run in the final frame.
Mariners starter Joe Saunders gave up nine hits and three runs in 5 1/3 innings for Seattle, but continued a strong July during which he's now 4-0 with a 1.73 ERA in four starts. The win elevated the 32-year-old lefty above the .500 mark for the first time this season at 9-8 with a 4.28 ERA.
This time the veteran didn't have his best stuff, but welcomed the production of Seattle's surging offense.
"As I've said in the past, it's just a matter of us doing the little things. And right now, we're doing the little things," Saunders said. "We're throwing the ball good, we're getting strikeouts when we need strikeouts and double plays when we need double plays. And we're getting clutch hits.
"It's all about situational hitting and we're doing that real well right now. We're hitting with guys in scoring position, which is key, and we're not giving away at-bats. Put that all together and good things are going to happen."
Saunders' worst start of the year came in his last outing in Houston when he got lit up for eight runs and 11 hits in five innings in late April. He wasn't very sharp again Friday, putting runners on base every inning and combining three walks with his nine hits before giving way to Yoervis Medina with one out and the bases loaded in the sixth.
"Honestly I just felt like everything was heavy," Saunders said. "My body felt a little sluggish. I was up for the game, just everything felt body-wise heavy. ... It's one of those nights where you have to pitch with what you've got and I tried to do that the best I could."
Center fielder Brandon Barnes hit for the cycle for the Astros, sliding into second on a hustle double to complete the feat in the eighth off Danny Farquhar on his way to a 5-for-5 night. It was the eighth cycle in Astros history and first since 2006.
Houston closed the margin with three runs in the eighth off Farquhar and Oliver Perez, including a two-run blast by Brett Wallace off Perez before Wedge brought in closer Tom Wilhelmsen with two on and two out. Wilhelmsen retired Chris Carter on a ground out to third, then finished things off in the ninth for his 20th save.
Rookie catcher Mike Zunino, who had walked four times in his first 24 games in the Majors, drew three base on balls as Seattle batters received eight free passes to go with eleven hits.