SEATTLE -- George Kirby’s distaste for walks has been well-chronicled. Even so, the Mariners’ uber competitive and cerebral starting pitcher showed more frustration than usual when issuing an eight-pitch free pass to the Tigers’ Riley Greene on Saturday night.

That’s perhaps because Kirby, who began the sequence ahead 0-2 in the count, is keenly cognizant of the potential for what free baserunners can lead to. This one continued a two-out rally in the fifth inning.

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Two batters later, Detroit’s Kerry Carpenter connected on a 95.2 mph fastball well above the strike zone for a 431-foot, three-run dagger of a home run that sent Seattle toward a 6-0 defeat at T-Mobile Park, securing its first series loss this month.

By the time Kirby got out of the jam, and beyond just his third walk with two outs this year, the Mariners were in a six-run deficit -- and still seeking their first hit against Detroit’s lone All-Star, Michael Lorenzen. Jarred Kelenic broke through with a one-out single in the fifth, but by that point, Mariners reliever Justin Topa was warming to signal the end of Kirby’s confounding night.

Even for an offense that has struggled with situational hitting, six runs was going to be a mountainous climb, one that Seattle hasn’t overcome since surging back from down seven on July 26, 2021, against Houston. Seattle had just two other hits after Kelenic’s but walked six times.

“We're not swinging the bat -- it's as simple as that,” manager Scott Servais said. “You've got to have more competitive at-bats, and we just got nothing going tonight.

“Unfortunately, it's kind of a recurring theme here throughout the year. We'll put a good run together, play really good for seven, eight, 10 days, and then we follow it up, we just can't sustain it.”

The six runs were Kirby’s second-most in a 2023 outing, behind only the seven he surrendered against Pittsburgh on May 26. He also gave up another homer to Carpenter in the second inning, a leadoff drive that opened the scoring. It was Kirby’s second multi-homer outing of the year, joining that start against the Pirates, when he gave up four. But in the seven starts in between, Kirby carried a 2.64 ERA, 38 strikeouts and four walks.

“I just didn't think I really executed well tonight,” Kirby said. “I kind of left a lot of things down the middle. My two-strike execution wasn't great.”

Seattle, which was the lone American League team with two All-Star starting pitchers, opened the second half behind those two arms and lost each game to begin this crucial 10-game homestand that could have big implications on the Trade Deadline outlook.

On Friday, Luis Castillo -- who didn’t pitch in the Midsummer Classic -- also surrendered two homers and lasted only five innings, though he surrendered only two additional hits. Castillo’s outing was more defined by Detroit laying off good pitches and pushing up his pitch count. 

“I give them [credit],” Castillo said Friday via interpreter Freddy Llanos. “The home runs that they did it, the balls weren’t exactly where I wanted, but I think the location wasn’t bad.”

Kirby’s evening, however, was plagued by the two-out production in the fateful fifth. Seattle’s righty surrendered a one-out double to Eric Haase then the two-out walk, which prompted a mound visit from Mariners pitching coach Pete Woodworth. Two pitches later, Kirby gave up a single to Spencer Torkelson that made it a 3-0 game, on a two-seamer running in but up.

And then Carpenter ambushed the fastball in a 1-1 count that was at his shoulders, not by any means a middle-middle mistake -- but nonetheless costly. Kirby’s other run was also with two outs, an opposite-field double by Greene that allowed Zach McKinstry to race home from second and beat out a 96.2 mph seed from Kelenic, but that only made it a 2-0 game.

As the Mariners turned things around following a disappointing series loss to Washington on June 28, Servais has preached the importance of winning series rather than getting caught up in the stakes of the long season and the looming Deadline. They’d done so against playoff contenders -- Tampa Bay, San Francisco and Houston -- leading into the break.

But the Mariners won’t get a chance to win their next series until after Detroit leaves town. In the interim, they’ll look to avoid a sweep on Sunday.