5 dark-horse teams primed for a postseason run

If the postseason began today, half of the 10 entrants would be teams that didn't advance to the October dance a year ago. That qualifies as a season loaded with standings surprises, but of course we know better than to assume there aren't any more surprises in store.
The following is a rundown of five clubs currently on the outside of that playoff picture who, for one reason or another, have a realistic chance of getting in. (Postseason probabilities are updated daily on MLB.com and can be found here.)
Brewers
Record: 59-55, 1 game back in the National League Central, 5 1/2 games back in the NL Wild Card standings
Postseason probability: 12.7 percent 
Can you really label a team just half a game back in its division a "dark horse"? In this case, you can. For one, FanGraphs gives the Brewers just a 4.3 percent chance of winning the division, with the Cubs at 88.1 percent. That speaks to the general assumption of how things will play out in the NL Central -- especially after a Trade Deadline in which Chicago improved considerably and Milwaukee was pretty quiet.
But even if the Cubs do separate themselves in the Central, as expected, the Brewers could push the Rockies and D-backs for the NL's second Wild Card spot. They just had a week in which their pitching staff allowed just 10 runs in 53 innings of work. Milwaukee really needs to get the bats going (Travis Shaw, Eric Thames, Ryan Braun and Domingo Santana have all been in a deep funk at the same time, and Shaw was injured when a ball struck his head on a stolen-base attempt Saturday). But 12 of the Brewers' next 15 are against sub-.500 squads. The other three games are against the Rox. Because Milwaukee isn't especially stretched financially, it is an interesting candidate to make a waiver-wire add this month. If the Brewers can acquit themselves pretty well these next couple weeks, they'll be in for an interesting September.
(For what it's worth, FanGraphs actually still gives the Cardinals a better chance of reaching the postseason than the Brewers. This seems suspicious, considering the Cards haven't been a .500 team in more than two months, are 20-28 within the NL Central and didn't do anything at the Deadline to improve what has been a bad offense all year. But sure, St. Louis might be a dark horse here, too.)

Rays
Record: 58-55, 5 1/2 games back in the American League East, tied for second AL Wild Card
Postseason probability: 33.6 percent, with a 3.6 percent chance of winning the division
This is a reverse of the Brewers' situation. The Rays are no dark horse in the Wild Card race, as they're neck and neck with the Royals. But the dark-horse label definitely applies in the AL East race, in which they are very much capable of upending our collective Red Sox-Yankees infatuation. That might have to begin this week, with a two-game set against Boston. The Rays still have eight games left with the Sox and six with the Yanks, so the opportunity to rise in the East is still very much in front of them.
Here's the primary problem: The Rays have been pretty anemic offensively in the second half, averaging just 3.5 runs per game. Logan Morrison and Corey Dickerson have more closely approximated their career norms than their All-Star-caliber production of the first half. But if those guys can get it going again, the addition of Lucas Duda (1.126 OPS since the trade) has lengthened a lineup with a lot of home run potential. It's just a matter of that lineup running hot in those ultra-important head-to-heads.

Orioles
Record: 56-56, 1 1/2 games back in the AL Wild Card standings
Postseason probability: 6.0 percent chance of reaching postseason
The Orioles' debatable Deadline strategy was to add (Jeremy Hellickson and Tim Beckham) rather than subtract. But hey, maybe they were on to something. Hellickson was brilliant in his Baltimore debut against the Royals last week (five hits and a walk allowed over seven scoreless innings), and Beckham has been an excellent fill-in for the injured J.J. Hardy, with 14 hits (including seven extra-base hits) in his first 24 O's at-bats.
Combine those upgrades with the sudden return of a good Ubaldo Jiménez, some great work of late from Kevin Gausman and Dylan Bundy and runs aplenty, and the Orioles have won seven of their past nine games. It's taken that run just to get within two games of an AL Wild Card spot, and it might be wise to bet on the larger sample when it comes to the rotation (though credit to the O's for doing the hard-but-necessary thing in demoting Chris Tillman to the bullpen). But it seems this club's best moments in the Buck Showalter era have come when the doubt is at its height, and that was definitely the case around the Trade Deadline.

Angels
Record: 55-58, 3 games back in the AL Wild Card standings
Postseason probability: 12.7 percent chance of reaching postseason
Is there any hope of us seeing Mike Trout in the postseason this year? Well, unsurprisingly, Trout is doing his part to try to make it happen, contributing a .361/.465/.597 slash line in his first 19 games since coming off the DL. And the Angels are still mathematically alive because they went a respectable 26-27 when he was hurt.
If the Halos have any real hope of ascending into October, they'll need their injured pitchers to experience a Trout-like return. Tyler Skaggs (rib cage) came off the shelf over the weekend, Andrew Heaney (2016 Tommy John surgery) is on a rehab assignment and Garrett Richards (biceps) is throwing bullpen sessions, so all of those guys could have an impact down the stretch. Of course, as Skaggs' somewhat ragged return against the A's (three runs on six hits over four innings) reminded us over the weekend, it can take time to iron out the wrinkles. Time might be a luxury the Angels don't have, but the potential improvement of this pitching staff is a situation worth keeping an eye on.

Mariners
Record: 57-56, 1 game back of AL Wild Card
Postseason probability: 22.1 percent chance of reaching postseason
Yeah, not exactly going out on a limb here. The Mariners could have jumped into an AL Wild Card spot -- and therefore been ineligible for this list -- by sweeping the Royals in a doubleheader Sunday. Instead, they split, so we'll include them here, which just goes to show how capricious this stuff is right now.
Anyway, Seattle is a really interesting club, vying to end the game's longest October drought. Losing ace Félix Hernández to a biceps injury over the weekend doesn't help matters, but the healthy James Paxton has basically been their statistical ace this season, and their staff has the fourth-best ERA (3.68) in the AL in the second half. The Mariners acquired Yonder Alonso on Sunday to aid their poor first-base production against right-handed pitching. Jerry Dipoto just keeps wheeling and dealing, trying to make this thing happen. Seattle hasn't been more than two games above .500 at any point this season, but the pulse of a city starving for October baseball could the team reach new heights down the stretch.