The surprises will keep coming, all the way through October. For now, let's look at the remaining contenders and the stretch-run surprise guys who are leading their final playoff push.
Here, in no particular order, are 10 of them:
1. Martinez, Tigers: Martinez is on this list not because of the way his arrival lifted a Tigers team suddenly starved for power early in the season, but for the way he has reignited himself in the heat of the American League Central division chase.
Martinez had a .255/.298/.408 slash line in his first 42 games after the All-Star break, so it was fair to wonder if he was coming back down to earth, as so many other surprise guys do. But Martinez's .373 average and 1.102 OPS in September have been instrumental in Detroit's fight to fend off those pesky Royals.
2. Derek Jeter, Yankees: Mathematically, the Yanks are probably in trouble, and Jeter himself has looked for much of the season as if he's coming toward the end. A week ago, he had the third-lowest OPS (.595) of any qualifying player in the big leagues, and there is little question the Yankees' decision to stick with him in the No. 2 spot put them in a precarious spot in a season in which they've been a fringe contender.
But we do have to give credit to Jeter for surprising us one last time. The Captain has hit .417 with a homer, three doubles and six RBIs to help the Yanks win five of six, ensuring that his final home games at least have some mathematical meaning. It's probably too late to get Jeter to one last October, but he's going down fighting.
3. Jon Jay, Cardinals: St. Louis has the second-best record in the National League since Aug. 1, trailing only the Nationals. And Jay, with a .336 batting average and a .425 on-base percentage -- the fourth-best mark in baseball in that span -- has arguably been the team's biggest offensive sparkplug.
The Cards entered this season having acquired Peter Bourjos to play center field, with Jay, whose defense and sagging bat were big issues last season, essentially cast aside in a fourth outfielder role. (And even that spot was tenuous, with prospects Oscar Taveras and Randal Grichuk on the way.) But Jay fought himself back into a starting -- and, eventually, starring -- role for a Cardinals team that surged back to the top of the NL Central standings.
4. Jake Peavy, Giants: Even if you thought the veteran Peavy's command/control arsenal would profile better in AT&T Park than it did in Fenway, you still have to be a bit surprised by just how much he's meant to San Francisco in the stretch run.
Peavy had a 4.72 ERA in Boston. But his 2.00 ERA dating back to Aug. 1 ranks 10th in the bigs, right behind the 1.96 mark put up by Dodgers ace Clayton Kershaw in that span. Peavy pitched effectively in the Giants' huge 5-2 win over the Dodgers on Monday night, and he'd probably be their No. 2 October starter, depending on how Bruce Bochy opts to align things. The veteran righty has been a huge addition for a team that had Matt Cain go under the knife, banished Tim Lincecum to the bullpen and saw big-time regression from Tim Hudson.
5. Steve Pearce, Orioles: Pearce has 20 homers in just 327 at-bats, and he's been a big part of Baltimore's story most of the season. And like Martinez, Pearce is really stepping up in crunch time for a team with legitimate World Series aspirations.
So much of the O's offense is homer-dependent, which is why the absence of Chris Davis, even with his sub-.200 batting average, has the potential to loom large in the postseason. But Pearce -- a 2012 waiver claim who was released and re-signed in a three-day span in April -- is proving all the more essential now that Davis is out for at least two postseason rounds. Though he's been out the past couple days with wrist issues, no player in baseball has a higher September OPS than Pearce's 1.221 mark.
6. Carl Crawford, Dodgers: A speed-based skill set such as Crawford's notoriously doesn't age well, and Crawford's seven-year, $142 million contract signed with the Red Sox before 2011 was -- and maybe still is -- looking like an albatross. Crawford spent much of the season's first four months of '14 either injured or appearing best suited to a reserve or platoon role.
But in a desperate attempt to improve his erratic offense, Don Mattingly opted to make Crawford his regular left fielder in late July, with Andre Ethier shifting to fourth outfielder status. Crawford's improvement since then has been dramatic. In his last 49 games, Crawford has a .346/.381/.494 slash line. In September, with the Giants still knocking on the Dodgers' door, Crawford has been even better: .414/.429/.707. This is the best Crawford has looked since he left Tampa Bay.
7. Brandon Finnegan, Royals: Wade Davis' sensational relief season is a surprise all its own, and the quick maturation of Danny Duffy and Yordano Ventura is a big reason why the Royals are pushing for their first postseason appearance in 29 years. But how about the way 21-year-old TCU alum Finnegan is stepping into a prominent relief role mere months after the Royals took him in the First-Year Player Draft? Ned Yost is trusting the kid in increasingly high-leverage situations, and Finnegan -- with 5 1/3 scoreless innings in which he's struck out eight, walked none and allowed just three hits -- is rewarding that faith. Finnegan will probably be Kansas City's go-to lefty option out of the 'pen in October.
8. John Holdzkom, Pirates: Pittsburgh has no shortage of surprise stars, which is why the club is in position for its second consecutive postseason appearance. Harrison was a surprise All-Star, and he took his game to yet another level in the second half. Vance Worley helped rescue the rotation with quality innings after a miserable year with Minnesota. You might even say Starling Marte's second-half surge qualifies as a surprise, given his previous relative struggle to meet expectations.
But as far as surprise stories go, it really doesn't get any better than Holdzkom. Pittsburgh scout Mal Fichman discovered the former fourth-round pick pitching for Amarillo in the independent American Association in June, and he was instantly intrigued by his velocity and presence. The Pirates signed Holdzkom, watched him dominate in the Minors and called him up this month. In eight shutout innings, he has given up just two hits, walked two and fanned 12. The Bucs' bullpen, once floundering in the middle innings, is now flourishing. Holdzkom, who looks like a lock for their postseason roster, is a big -- and surprising -- reason why.
9. Carlos Carrasco, Indians: The Tribe's barely breathing playoff hopes might very well have been read their last rites Monday night, when the Royals shut them out at Progressive Field to extend their AL Wild Card lead to 3 1/2 games. But that was through no fault of Carrasco, who allowed just two runs over 7 1/3 innings and didn't get much defensive help. This was on the heels of Carrasco's near no-hitter during his previous outing in Houston, in which the only two Astros hits were infield singles by Jose Altuve.
All told, Carrasco has a 1.32 ERA in nine starts since rejoining the Indians' rotation in August, proving a worthy No. 2 to AL Cy Young Award candidate Corey Kluber. Considering Carrasco's 6.95 ERA in four April starts and the inconsistency that had hampered his big league career, this late-season run was truly unforeseen, and it was a big reason why Cleveland got to the final week of the regular season with something to play for.
10. Drew Storen, Nationals: Ultimately, maybe it's no surprise to see Storen usurp closing duties from the struggling Rafael Soriano in September. But Storen has nonetheless taken his surprise story to yet another level, in that he'll enter October as arguably the most effective closer on any playoff team. He has earned his part in the conversation by allowing zero runs and a .190 average against in his past 17 innings (covering 20 appearances), dating back to Aug. 7. Storen has reinvented himself with the incorporation of a changeup into his repertoire, and now he's positioned to make the 2012 postseason blowup a distant memory.