SEATTLE -- It was as tough of a situation as any Mariners reliever has faced all season, and it ultimately proved to be too tall a task to overcome.

Drew Steckenrider entered the eighth inning Tuesday night to face the heart of Boston’s loaded lineup after Joe Smith served up a leadoff single to Xander Bogaerts. Steckenrider immediately found himself battling against a lineup that wouldn’t bite at his best weapon, the elevated fastball.

The right-hander nibbled his heater above the zone, which led to walks to Rafael Devers and Travis Shaw. Then he steered one a little too much over the plate and served up a bases-clearing dagger of a double to pinch-hitter Kyle Schwarber, which wound up breaking things open in an 8-4 loss at T-Mobile Park.

• Box score

Yohan Ramirez was then called on and gave up a two-run homer to Alex Verdugo that served as the nail in the coffin and evened this vital series for these teams that entered the night as the first two clubs on the outside looking in for the second American League Wild Card spot. Boston also tallied another run in the ninth off its former teammate, Matt Andriese, for good measure.

The Mariners fell to three games behind the Red Sox, who moved into a tie with two AL East rivals, the Yankees and Blue Jays, for a postseason berth.

“At this point in this season, every situation is a tough situation,” Steckenrider said. “Being in the playoff hunt, every out is crucial. There's no outs that are more important than any other outs. Everything means the same right now. So in that case, from pitch one, everything is just as important to the end of the game.”

This game was far tighter than the box score indicated, at least until the fateful eighth.

In this tightrope of pennant-chase, September baseball, the leadoff triple to Bogaerts loomed as large as any moment of the night. Smith, who’d just polished off a 1-2-3 seventh with two strikeouts, left a sinker at the top of the strike zone that Boston’s All-Star skied into the right-center gap, creating a play that -- albeit an awkward fly -- was one that Mitch Haniger appeared to be in position to make.

Whether it was lost in the lights or via an odd turn, Haniger wound up overshooting the play and crashed into the wall as the ball dropped in. According to Statcast, the play had a 60% catch probability, indicating it was a tough, but not impossible catch.

After Haniger gathered himself, Mariners manager Scott Servais relieved Smith for Steckenrider, who stared down a lineup that wouldn’t budge.

“That's about as tough as it gets, there's no question,” Servais said of Steckenrider’s sequence. “Certainly, we liked the Devers matchup and then you're not anticipating a guy hitting a leadoff triple, for sure. Steck really battled tonight, he did. He did not give in.”

Though Steckenrider was on the hill for the game-changing moments, Smith took the brunt of the blame for putting him in that spot. The 14-year veteran who has been with Seattle for less than two months spoke with reporters before Steckenrider to cover his teammate.

“He's been absolutely unbelievable for us all year, and especially since I've gotten here,” Smith said of Steckenrider. “And [Bogaerts’ triple] just puts him in a spot where he's got to make the perfect pitches. What we saw from him tonight was not him, and it's not how he pitches. But I mean, that's on me.”

The seven runs surrendered by the Mariners’ bullpen -- the Majors’ best this season by WAR -- were its most since an 11-4 loss to Houston on July 28. Before that, Seattle relievers hadn’t given up that many runs in a single game since June 5 against the Angels.

And the runs surrendered by Steckenrider were his first since Aug. 4.

Seattle’s bullpen has been strong all season, but even Servais discussed pregame how diligently the Mariners are monitoring their innings in this final month. And shortly after that discussion, his relief corps was staked with covering more than half of the innings Tuesday after Tyler Anderson labored his way to 90 pitches in 4 1/3 frames.

All season, the Mariners -- especially their bullpen -- have been able to flush tough losses, and that’s what they’ll attempt to do Wednesday in the series finale.