OAKLAND -- Cal Raleigh passed his longtime mentor and current manager in the record books with his 84th RBI, setting a new Mariners benchmark for the most in a single season by a catcher. Later on, Victor Robles made arguably Seattle’s catch of the season that, for good measure, ended with him doubling up the runner on first base.

But those were the Mariners’ only bright spots in a 3-2 walk-off defeat to the A’s that extended their skid to four games, one shy of their season-worst. The timing of this losing streak, though, is far more dire.

The Mariners (69-70) are below .500 for the first time since entering play 9-10 on April 20, punctuating a summer-long spiral into September, with the blunt reality of mathematics dwindling their hopes of extending this season into October.

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They fell to a season-high 6 1/2 games behind the idle Astros in the American League West with 23 games remaining. They remained 5 1/2 games back of the final AL Wild Card spot, with the Red Sox and Tigers -- both of whom hold a tiebreaker over Seattle -- in between.

“I don't know if ‘slipping away’ is the word,” Raleigh said of Seattle’s reeling playoff odds, which trimmed to 4.8%, per FanGraphs. “I think ‘frustration’ is the word we use. It's just frustrating, because we're in these games.

“It's not like we're getting blown out each day or that we're not getting a chance from our starters. We're in these games. We're playing close games. We've just been not winning. We're not finishing. We're not playing the full nine [innings]. I think that's the big thing.”

Indeed, these stockpiling losses of late have essentially all been of the gut-punch variety.

Tuesday’s was manufactured when Trent Thornton surrendered a screaming, game-winning single up the middle to Seth Brown on a middle-middle fastball, which was set up by a one-out walk to JJ Bleday and a knock through the left-side hole from Shea Langeliers, who crushed the walk-off homer in Monday’s loss.

Thornton was called upon over Collin Snider, who was also warming and would’ve been turned to with a lead. There was speculation why Andrés Muñoz wasn’t considered, but the All-Star closer revealed postgame that he’s been experiencing elbow soreness and that he was only going to be deployed with a lead in these first two games in Oakland. He was warming in the ninth on Monday and downplayed the severity of the issue.

All said, though, two runs was never going to be enough, as Raleigh acknowledged postgame.

He put them on the board with a two-run single as part of a three-hit first inning, which pushed his RBI total past Dan Wilson’s franchise-best 83 from his All-Star season in 1996. But the Mariners went 2-for-22 the rest of the way and didn’t reach scoring position again until the seventh, their final time doing so.

Their most stinging moment came in the ninth, when Justin Turner was called for strike three instead of ball four on what he believed was a check-swing, expressing frustration postgame that home-plate umpire Manny Gonzalez did not appeal to first-base umpire Tom Hanahan, given that the pitch was well below the strike zone.

Randy Arozarena, who was on first base and took off on the pitch, appeared to believe it was a walk, too, as he slowed to a near halt before reaching second and was easily thrown out for a caught-stealing.

“I was watching the pitch, so I didn't really see what happened,” Wilson said. “I was focused on the umpire trying to understand what was going on with the check-swing.”

Three of the Mariners’ past four losses have come in walk-off fashion, dating back to last weekend in Anaheim. Going back further, all of their past six losses -- all since Wilson took over for Scott Servais on Aug. 22 -- have all been by one run. That streak is tied for the longest in franchise history, dating back to a stretch from May 12-21, 1993, per Elias.

Overall, the Mariners -- who led MLB in one-run victories in 2021 and 2022 -- are tied with the Pirates for the most run-games played in this year (47) but are also tied for fifth-most in losses (24) in such contests.

“Nobody is rolling over, and we're not [saying] that we don't still have a chance, because we do,” Raleigh said. “Like I said, crazier things have happened. But we're going to have to get on a roll. We've got to get going.”