The Seattle Mariners are tied for the second American League wild-card spot and on the cusp of an elusive playoff berth heading into the final series of the season.

Long stuck in the doldrums, the Mariners are suffering through the longest playoff drought of any major American sports team. There were signs coming into 2021 that prodigious transaction-maker Jerry Dipoto had assembled the makings of a club that could mercifully erase the Mariners from that embarrassing TV graphic, it just looked like that club would take the field in 2022 or 2023.

And by most of the indicators that we might usually use to identify a good baseball team, that estimate still looks right.

See, the 2021 Mariners have been handily outscored by their opponents. Teams with Seattle’s -48 run differential would be expected to post a 75-84 record — similar to the dismal, disappointing New York Mets … who have only a -36 run differential this season. These Mariners, though, are 89-70 and banging down the door to October as Boston Red Sox and New York Yankees try to hold firm.

How rare would it be if the Mariners make the playoffs?

If the Mariners do snag a spot in their first postseason since 2001, they would become just the 10th team in MLB history to do so with a negative run differential. But it’s actually even more incredible than that.

Three of the nine playoff clubs that were outscored pulled the trick in 2020 with an expanded postseason and shorter, flukier season. Only six teams had done in prior to that, with three coming in the wild-card era since 1995 and three coming in the prior era of even smaller playoff formats. Only one went on to win the World Series, the 1987 Minnesota Twins. Here’s the complete list:

• 2020 Marlins, -41

• 2020 Brewers, -17

• 2020 Blue Jays, -10

• 2007 Diamondbacks, -20

• 2005 Padres, -42

• 1997 Giants, -9

• 1987 Twins, -20

• 1984 Royals, -13

• 1981 Royals, -8 (strike-shortened season)

The Mariners could very well post the worst run differential of any playoff team ever. That won’t change the jubilation and relief for a fan base that has reason to be optimistic going forward.

Top prospect Jarred Kelenic, acquired in a fleecing of the New York Mets, has an ugly stat line in his debut season but has shown marked improvement lately. Since Aug. 1, he has been an above-average hitter, smashing 11 homers and walking more than 10% of the time. Fellow rookie Logan Gilbert has a 2.70 ERA on the mound in six September starts, five of which have resulted in Mariner wins.

The most recent of those completed a momentous sweep of the Oakland A’s (run differential: +61). Now Seattle — winner of four in a row and nine of 10 — will head into a three-game set with the Los Angeles Angels in a dead heat for the second wild-card with the Red Sox, who couldn't hold serve against the lowly Baltimore Orioles this week.

How does this happen?

The charmed path of the 2021 Mariners is pretty much just that, charmed. That became most evident on Aug. 31. A month after Dipoto infuriated his own team by trading closer Kendall Graveman to the division rival Houston Astros for the younger infielder Abraham Toro, the two clubs were locked in a scoreless tie in the eighth inning.

Up came Toro with the based loaded. Against Graveman.

This is what distinguishes the Mariners: They have been outlandishly good at hitting when the moment is biggest. Overall, Seattle’s offense is a lowly 26th in OPS this season, batting a collective .226/.302/.386 for a .688 mark. Even adjusting for park, their output ranks just 20th. But in high-leverage situations (broadly, moments where the outcome of the game is most up for deciding), the 2021 Mariners morph into the league’s best lineup. In these key situations, which often entail facing the best pitchers the other team has to offer, they have an MLB-leading .833 OPS.

Over and over again, baseball researchers have failed to find any true skill or repeatability in players or teams who step up their games in decisive at-bats — the phenomenon is often fleeting, or clustered by happenstance. But given the choice of how to spread out a limited amount of possible production, this is how you’d do it!

This degree of clutch performance — which compares how they play in big moments to their own norms — is unprecedented. They hit like Cesar Hernandez as a whole, but like Jose Altuve when it matters most. By Baseball-Reference’s calculations, the Mariners are on pace to be the most clutch lineup of all-time.

The biggest contributors to that include Ty France, the flexible infielder proving his 2020 breakout was for real, and Luis Torrens, a catcher-turned-DH whose league-average production would be a pleasant surprise even if it did not include a double-take-inducing .391/.437/.703 line in 71 high-leverage plate appearances. Seattle stalwart Kyle Seager — whose distinguished career has thus far included zero playoff games — has 45 RBIs in these key moments, fifth-most in baseball.

Bullpens are also usually a major factor when teams over perform like this. And while the Mariners aren’t going bonkers with relief arms like the early 2010s Orioles or anything, they have gotten surprising star turns from Paul Sewald (2.73 ERA and the fifth-best K-BB% among relievers) and Drew Steckenrider (13 saves with a 2.06 ERA). Late in close games — like in those frames right after a high-leverage comeback — the Mariners pitching staff has held hitters to the second-worst OPS in baseball, behind only the San Francisco Giants.

Three games and a tangle of playoff scenarios now stand between the Mariners and a wildly unlikely playoff appearance. For a franchise plagued by an ever-ticking clock, a salve born of absurdly good timing would surely be acceptable.