In the last week of August, American League baseball was in a familiar state. The East was in line to take three of the league’s five available playoff spots, with the Rays, Yankees, and Red Sox all having at least an 89 percent chance of making the postseason, according to FanGraphs. Only two other teams were even in double digits, as if winning baseball had just never found out about the Louisiana Purchase.

That’s pretty much been the norm for the past 15 years. Boston and New York, baseball’s greatest historic rivals, wallop each other in pursuit of a playoff berth, while the Rays swirl around the playoff hunt like the antioxidants in a fancy fruit smoothie—everyone says they’re good, few can articulate exactly why. The division’s bird-associated teams might come up to steal a worm every now and then, but those years tend to be exceptions.

Since August 28, though, the Blue Jays have won 11 of 12 games, including four in a row against the Yankees, to cut their deficit in the wild-card race to just half a game. In the span of two weeks, the Jays have gone from having a roughly 1-in-20 chance at making the postseason to being more or less a coin flip. Like George Washington in the old-timey cartoon: Opponents beware, the Blue Jays are coming, they’re coming, they’re coming.

Anytime the standings close up this quickly, there are many causes. But more than anything, Toronto’s rapid resurgence is the function of the Blue Jays having been a playoff-quality team all along. Through Wednesday’s games, Toronto’s run differential sits at plus-143. Not only is that the third-best mark in the AL and the fifth-highest in MLB, but no team with a run differential that good has missed the playoffs since 2005.

Run differential isn’t some kind of mathematical steamroller that guarantees the Blue Jays a postseason berth. But it’s an indicator of underlying quality. This is a team built to upset the established power structure and to trouble its southern rivals. And after a tumultuous first five months of the season, the Blue Jays still have a chance to make good on their potential.

Every team, however talented, runs into unexpected obstacles during the season—and the 2021 Jays are no exception. Star free-agent signing George Springer got hurt. Vladimir Guerrero Jr. started dragging after an MVP-quality first half. Humongous Floridian youth Nate Pearson couldn’t stay healthy enough to claim a rotation spot, while Bo Bichette and Hyun-Jin Ryu declined from superstar-level in 2019 and 2020 to merely good in 2021. Lourdes Gurriel Jr. was lost at sea for the first six weeks of the season, and Cavan Biggio went from hitting .240/.368/.430 in his first two big league seasons to .215/.316/.350 in 2021. Then he got hurt too.

When a team underperforms its run differential, the most common explanation is a bad bullpen. Toronto’s bullpen isn’t awful on aggregate (seventh in MLB in ERA-, 17th in WPA), but it’s been an inconvenience. Last winter, the Blue Jays attempted to replace injured closer Ken Giles with Kirby Yates, but Yates ended up needing Tommy John surgery. Julian Merryweather’s 100 mph fastball made him a seemingly ideal replacement, but he too ended up on the IL with a muscle strain in mid-April and made it back to the majors only this past week. (Oblique is both the muscle Merryweather injured and a fair way to describe his path to recovery.)

In an attempt to compensate for this bad luck, Toronto traded catcher Riley Adams to Washington for reliever Brad Hand at the deadline. Adams is now hitting .327 with power as the Nats’ de facto starting catcher, while Hand went 0-2 with a blown save in 11 relief appearances with Toronto. Hand also allowed a 7.27 ERA and an opponent slash line of .351/.390/.622 in those appearances. And the past tense is correct here, because after just five weeks, Toronto GM Ross Atkins cashiered the veteran left-hander, who lilted down the waiver wire until he eventually ended up with the Mets.