SEATTLE -- For the second straight night, left-handed reliever Reymin Guduan was brought in to face slugging lefty Daniel Vogelbach, and again, the Mariners slugger left with the upper hand.

Guduan entered Wednesday’s game in the sixth inning with Seattle leading 2-1, but after walking Vogelbach -- a night after he surrendered a bases-clearing triple to the Mariners’ DH -- Guduan served up a two-run homer to Domingo Santana and a single to another lefty, Shed Long, that helped spark the Mariners in a runaway 14-1 win -- the Astros’ most lopsided loss since a 17-2 defeat to the Tigers on May 2, 2013.

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Between closer Roberto Osuna and Ryan Pressly, who have been unscored upon in 47 of their combined 53 appearances, the Astros have arguably the best back-end bullpen in the American League. Will Harris (1.23 ERA) and Hector Rondon (2.57) have also been strong. But on Wednesday, manager AJ Hinch was hoping to give his bullpen mainstays a breather.

“Most of the game, I was going into it not wanting to use our primary guys,” Hinch said. “We've worked them a ton, so some other guys have to pitch on a daily basis and they struggled tonight and it got really ugly.”

Such was the case on Wednesday, when Brad Peacock entered the fifth with a 1-0 lead and gave up a leadoff walk. He worked his way into a bases-loaded jam with no outs and managed to limit damage, but not until after he gave up a two-run double to Mallex Smith. Tyler White’s first-inning sacrifice fly that scored Alex Bregman was all the support the Astros provided their pitchers.

“It's a tough loss for him because he pitched better,” Hinch said of Peacock. “The score is going to look up on the board that it was a blowout and it was actually really close when he was in there.”

Houston mustered just six total hits, all against Mariners starter Mike Leake, who threw the American League’s eighth complete game of 2019, and the first for Seattle’s suspect pitching staff. Regular Astros starters Robinson Chirinos and Yuli Gurriel had scheduled days off.

Guduan was recalled on Tuesday to take the roster spot of Corbin Martin, who lost the No. 5 spot in the rotation to Framber Valdez, who will start on Saturday against Baltimore. Valdez was the club’s lefty specialist reliever before this week’s shuffle of the pitching staff, which leaves Guduan as the lone lefty in the Astros’ bullpen.

“My command has been good. Just the slider today wasn't falling the way I wanted it to,” Guduan said. “Unfortunately, that's part of the game. I need to do better next time around. These are things that happen in baseball and I need to maintain my confidence high and maintain my head high and attack the zone and keep doing my job.

Right-hander Brady Rodgers, who had pitched in just three innings before Wednesday, entered with a 4-1 deficit and gave up a two-run homer to the first batter he faced, catcher Tom Murphy. Rodgers wasn’t pulled until after he gave up a three-run homer, to pinch-hitter Mac Williamson, in the eighth. Peacock, Guduan, Rodgers and White faced a combined 30 batters from the fifth inning on, and Houston pitchers walked Seattle leadoff batters in the second, fifth, sixth, seventh and eighth innings.

In total, the Astros gave up 14 unanswered runs to Seattle after taking a 1-0 lead in the first.

Without their MVP caliber core (Carlos Correa, George Springer and Jose Altuve) and infielder Aledmys Diaz, the Astros have nonetheless marched on. Houston still retained first place in the AL West by nine games over the Rangers, after Texas beat the Orioles in 12 innings. After Wednesday, the club dropped to 20-6 against the AL West, which remains by far the best record of any team against its division in MLB this season. And since May 1, Houston is 23-8, which trails only the Dodgers (22-7) for the best record in that span.