SEATTLE -- Looking for a boost in the series opener against Houston, the Mariners went with an “opener” to start Monday in career reliever Cory Gearrin.

And the Astros shut the door on that pretty quickly.

Houston touched Gearrin for three runs in the first inning, a decisive scoring burst in Seattle’s 4-2 loss at Safeco Field.

• Box score

Josh Reddick had an RBI triple and Robinson Chirinos added a solo homer in the opening frame as Houston (41-20) took a lead it wouldn’t relinquish.

That made the best outing by Seattle lefty Wade LeBlanc something of a side note.

Gearrin (0-2) took the loss, allowing two hits and a walk before coming out. LeBlanc followed with eight innings of one-run ball in relief. Reliever Framber Valdez (2-2) earned the win for the Astros.

Seattle (25-38) dropped its third straight, as well as the 12th loss in their last 14 games.

“I would consider doing it again, no question about it,” manager Scott Servais said of the strategy. “It has a bit of a different feel to the ballgame, but as far as it working, certainly didn’t throw a [zero] in the first inning, that didn’t happen. But we got a lot out of our ‘starter’ tonight, I’ll take that every time out.

“Or follower, I should say.”

It was Gearrin’s first start in 295 games in professional baseball, in either the Majors or Minors.

Gearrin’s trouble came after getting ahead of hitters early, but not closing them out. He got ahead 0-2 on Alex Bregman, but Houston’s All-Star battled back to draw a walk. Gearrin then got ahead 0-2 on Reddick -- but after working to a full count, Reddick tripled to the wall.

After Reddick scored on Yuli Gurriel’s infield chopper, Chirinos followed with a no-doubt blast to left.

Gearrin finished his inning, allowing three runs (all earned) on two hits and a walk.

Servais was quick to point out that Gearrin largely did what he’d hoped -- getting ahead of the Astros’ batters early.

But most importantly, when LeBlanc took the mound, the Mariners were already in a hole.

“I don’t know if it necessarily helped,” LeBlanc said of his coming out of the bullpen. “There were things in the last 2-3 starts trending toward a quality outing.”

“Clearly Wade pitched unbelievable today, it’s tough on me,” Gearrin said. “As a bullpen guy, you want your guys to get wins when you pitch like that.”

The Mariners pulled two back in the third with solo homers from Mallex Smith (his third) and Edwin Encarnacion (his 16th).

The Mariners had their chances, especially early. But they were a combined 0-for-7 with runners in scoring position during the game.

“Pitching did tonight what we hoped they’d do,” Servais said. “Just not enough offensively.”

It was the first time this season the Mariners have used a true opener to start a game.

Seattle had lefty Yusei Kikuchi throw a one-inning start on April 26 against the Texas Rangers, a 5-4 victory. But that was part of a plan to have Kikuchi throw periodic abbreviated starts, so the rookie from Japan could get used to pitching more than once a week.

The last time the Mariners utilized an opener was last season on Sept. 19, when Matt Festa pitched an inning, coincidentally against the Astros. Festa was one of seven pitchers to combine on a five-hitter in a 9-0 victory over Houston.

Gearrin said pitching as an opener was something he’d be ready for if he got the call again.

“It’s frustrating, but going forward it’s part of the game and we’re seeing it more and more,” he said. “So as a pitcher, figure out how to go out and adjust on the fly."

Gearrin finished his inning, allowing three runs (all earned) on two hits and a walk.

Servais was quick to point out that Gearrin largely did what he’d hoped -- getting ahead of the Astros’ batters early.

But most importantly, when LeBlanc took the mound, the Mariners were already in a hole.

“I don’t know if it necessarily helped,” LeBlanc said of his coming out of the bullpen. “There were things in the last 2-3 starts trending toward a quality outing.”

“Clearly Wade pitched unbelievable today, it’s tough on me,” Gearrin said. “As a bullpen guy, you want your guys to get wins when you pitch like that.”

The Mariners pulled two back in the third with solo homers from Mallex Smith (his third) and Edwin Encarnacion (his 16th).

The Mariners had their chances, especially early. But they were a combined 0-for-7 with runners in scoring position during the game.

“Pitching did tonight what we hoped they’d do,” Servais said. “Just not enough offensively.”

It was the first time this season the Mariners have used a true opener to start a game.

Seattle had lefty Yusei Kikuchi throw a one-inning start on April 26 against the Texas Rangers, a 5-4 victory. But that was part of a plan to have Kikuchi throw periodic abbreviated starts, so the rookie from Japan could get used to pitching more than once a week.

The last time the Mariners utilized an opener was last season on Sept. 19, when Matt Festa pitched an inning, coincidentally against the Astros. Festa was one of seven pitchers to combine on a five-hitter in a 9-0 victory over Houston.

Gearrin said pitching as an opener was something he’d be ready for if he got the call again.

“It’s frustrating, but going forward it’s part of the game and we’re seeing it more and more,” he said. “So as a pitcher, figure out how to go out and adjust on the fly."