The newest, scariest competitor for the American League’s second wild-card spot should look familiar to Seattle fans anxious about the encroachers. They hit like the Mariners, after all, and they pitch kind of like the Mariners, and they win close games a lot like the Mariners, but—surprise!—they’re not actually the Mariners. The Oakland A’s are making a run at Seattle’s playoff spot, and they’re building momentum with a formula that looks a lot like the one Seattle used to stake a first-half lead.

The reality of an AL race at all is somewhat of a surprise, given how far ahead the five currently positioned playoff teams were just a couple of weeks ago. As recently as July 5, Seattle reached a season-high 88.3 percent chance of making the playoffs, according to FanGraphs projections, at a time when the other four AL contenders (Boston, New York, Cleveland, and Houston) were all nestled north of 99 percent. No other AL team was even in double digits.

Just two weeks later, though, the Mariners’ hold on the second wild-card spot has loosened, their lead falling from 7.5 games to just three, as Oakland is now just one favorable weekend from catching Seattle. By popular consensus, the A’s were an afterthought before the season—Vegas gave them the lowest over/under total and worst playoff odds of any team in the division—but by building on some budding 2017 strengths and capitalizing on a Mariners-style run of good fortune, they’ve been the best team in baseball over the last month and made the AL race fascinating.

First, on defense, Oakland is a working embodiment of the notion that it’s easier to improve from terrible to decent than from decent to terrific. In 2016, the A’s were likely the worst defensive team in the majors as measured by advanced stats defensive runs saved (30th in the majors) and ultimate zone rating (29th). In 2017, they were again maybe the worst (27th in DRS, 30th in UZR). In 2018, though, the defense has been at least competent, if not an outright strength; at the break, the team ranks 18th in DRS and seventh in UZR.

The most notable reason for this rise is that third baseman Matt Chapman, who made his MLB debut midway through last season, has already ascended to the top of the majors’ defensive hierarchy. Chapman leads all fielders at all positions in both DRS and UZR—made all the more impressive because those are both counting stats and Chapman missed 16 games with a right hand injury—and he looks every bit like peak Manny Machado or Nolan Arenado at the hot corner. Thanks to Chapman’s presence and improvement elsewhere in the infield, the A’s are tied with the slick-fielding Cubs as the most effective ground-ball defenses in the majors.

Chapman also has hit better than expected, and he slots into a lineup deep on solid production, if short on star power. Oakland’s only non-pitcher All-Star this year was second baseman Jed Lowrie, who paces the team with a 135 wRC+ but was perhaps the least heralded participant in Tuesday’s exhibition. And the team’s leading home run hitter is Khris Davis, who has been a consistently dependable hitter throughout his career but still carries less name recognition than the other MLB slugger whose name sounds like “Khris Davis.”

Oakland doesn’t have a flawless lineup—Marcus Semien leads the team in plate appearances despite running an 87 wRC+, and Jonathan Lucroy (69 wRC+) has continued his steep, multiyear decline at the plate—but all its pieces put together form an irrepressible group. The top six teams in wRC+ are five division leaders and the Yankees; seventh is the Mariners, and eighth is the A’s.

Seattle has a slightly better upper crust than the A’s, with Nelson Cruz besting Davis at DH and All-Stars Mitch Haniger and Jean Segura providing pop ahead of Cruz, but Oakland makes up ground with its depth. Seven Athletics with at least 200 plate appearances have a wRC+ at least 10 percent better than league average; only the Dodgers (eight) have more such players, and the Cubs (also seven), Astros (six), and Yankees (six) round out the top five.

Like the lineup’s leader, Oakland’s supporting bats are lesser known but no less productive. Matt Olson’s not knocking a home run every other game like he did in the second half last year, but as a decent hitter and Gold Glove favorite at first base, he’s still on roughly a three-WAR pace. Stephen Piscotty is hitting .309/.374/.590 since June 1 and has been a phenomenally clutch batter. And Chad Canha and Mark Pinder are perfectly, archetypally anonymous A’s hitters, so much so that their names are actually Mark Canha and Chad Pinder and it’s unlikely many readers batted an eye at the switch—but the difference doesn’t much matter because they’re both right-handed utility men with identical 120 wRC+ marks. (That means they’re hitting one point better than both Bryce Harper and Cody Bellinger.)

The pitchers weave a different story, as Oakland’s staff has been less reliable than reliably haphazard. No-hitter maestro Sean Manaea is the only one of 12 A’s pitchers with a start who has spent the entire season with the big league team. Every other starter has been hurt, in the minors, or both, as have promising young hurlers Jharel Cotton and A.J. Puk, who both underwent Tommy John surgery early in the spring.

The rotation has been so inconsistent that reliever Yusmeiro Petit has thrown the third-most innings on the team, and closer Blake Treinen is one frame away from moving into the top five. The current rotation includes Brett Anderson, back in Oakland after a half-decade wandering injury-ravaged lands, and Edwin Jackson, now pitching for his 13th team and, thus far, doing quite well with a 2.59 ERA in four starts. The Mariners parallels are evident here as well, with Seattle veteran Wade LeBlanc, one of the craftiest lefties in the stereotyped history of crafty lefties, pitching effectively enough to earn a contract extension earlier this month.

Those similarities extend to and really stand out in the bullpen, as each team has capitalized on a stellar back end to excel in close games. In one-run contests, the A’s are 15-8 for the third-best winning percentage in the majors while Seattle, at 26-12, is second. While the Mariners have rather publicly outperformed their Pythagorean record—which is based on run differential—by an MLB-leading 10 games thus far, Oakland is tied for second with a four-game gap.

Seattle closer Edwin Díaz has received plenty of attention as the MLB’s saves leader, and it’s warranted: He also leads all relievers in fWAR and ranks third in win probability added. But his counterpart in Oakland has been just as dominant, as Treinen—who, incidentally, has the exact same innings total as Díaz in 2018—places second in fWAR and first in WPA.

The closer-setup combination of Treinen and rookie Lou Trivino has received predictably little hype, despite its overwhelming statistical achievements this season. Treinen came to Oakland last season in the trade that sent established relievers Sean Doolittle and Ryan Madson to Washington, and he immediately rebounded from a rough 2017 stint in D.C. that left him with a 5.73 ERA through 37 games. Trivino, meanwhile, is a converted starter who was never touted as one of Oakland’s top 10 prospects, but even that descriptor undersells his anonymity. Earlier this season, SB Nation prospect writer John Sickels responded to a question from a reader asking, “Pardon the language, but who the **** is Lou Trivino?” with the answer, “Don’t feel bad, I do this stuff for a living and I didn’t know much (anything) about Lou Trivino until about nine months ago when he reached Triple-A.”

Yet among 164 qualifying relievers, Treinen ranks first in ERA (0.94) and Trivino third (1.22). Those figures will likely regress in the second half—particularly Trivino’s, as he’s benefited from an unsustainable strand rate and batted-ball luck—but the two right-handers aren’t valuable just because of their run prevention. They also shine with their ability to retain their effectiveness over more than one inning; in 14 appearances each in which they’ve recorded four or more outs, Treinen and Trivino have been just as stifling as a typical elite reliever over a three-out stint.

A’s Relievers in Multi-inning Outings Player Games IP ERA AVG OBP SLG Player Games IP ERA AVG OBP SLG Blake Treinen 14 25 0.36 0.183 0.216 0.226 Lou Trivino 14 25 1/3 0.71 0.149 0.211 0.218

Overall, Treinen has made 13 appearances of more than one inning when he didn’t allow a run. That’s tied for the third most among all relievers, behind fellow Oakland reliever Petit (15) and Milwaukee’s Josh Hader (14). Trivino, with 12, is tied for fifth. This multi-inning tendency generally separates Oakland from other top bullpens. Nobody from the Yankees has more than nine such appearances, nobody from the Red Sox has more than seven, and Collin McHugh is the only Astro with more than six. As a team, Oakland has 69 this season, tied with the Brewers for the most of any team. Conversely, Seattle, with just 26, has the fewest, with no individual reliever tallying more than five and Díaz managing just one all year.

In this area, then, the ability of the A’s and Mariners to get wins is more important than how they get them. And for Seattle fans worried that their team won’t maintain its lead and reach its first postseason since 2001, the fact both contenders are built upon a similar foundation—a solid offense, one reliable lefty starter surrounded by question marks, and lots and lots of close wins—should be heartening; if Seattle is doomed to regress, so too should Oakland.

In high-leverage situations this season, Mariners hitters have combined for a 130 wRC+—meaning the whole team, in the most important at-bats, has hit like Kris Bryant or Kyle Schwarber. Except Seattle is only tied for first place in this split: Oakland has also delivered a 130 high-leverage wRC+. Meanwhile, the most effective pitching staff in high-leverage situations belongs to Oakland outright; here, Seattle is tied for third place. There’s no reason to expect Seattle’s outrageous performance in clutch situations to last, but there’s no more reason to expect Oakland’s to sustain, either. The A’s are hot now, but no hotter than Seattle was earlier in the season. The Mariners’ three-game cushion, moreover, gives them an edge this far into the season, and the playoff odds reflect that disparity in showing a two-to-one Mariner advantage for the AL’s final playoff spot.

But it won’t be easy, with the two teams facing each other in 10 games the rest of the way and, crucially, Oakland seeing the Astros just six more times compared with Seattle’s 13. Oakland’s playoff odds reached a nadir on June 15, when the final loss of a four-game losing streak dropped the team to a 34-36 record and 11-game deficit against the Mariners. In the following month, though, the A’s went an MLB-best 21-6 while Seattle stumbled to a 13-14 mark, and, slowly, Oakland’s odds rose: 5.0 percent on June 19, 15.2 percent on July 9, and, finally, 30.9 percent after the last game of the first half. Even with Seattle’s existing advantage in mind, it’s hard not to view that creeping, rising line like a monster about to devour the Mariners’ 17-year dreams.

Oakland could well stumble down the stretch and leave Seattle unruffled and en route to its first playoff game since Ichiro Suzuki’s rookie year. But it seems more likely that the two teams’ fortunes will rise and fall together, just as their journeys to this point have traversed similar, if not synchronized, paths. Man has no greater enemy than himself, as the Mariners are learning in real time as a team that embodies their greatest strengths chases them down.