Before we dive in, a brief note: don't expect to find much credence given to "momentum." For every 2003 Marlins, surging to the finish and winning it all, there's a counter like the 1997 Marlins, who finished the year losing four straight and 15 out of 24.
The things that matter are more prosaic. Health helps. As do a dominant pitching staff and an airtight defense. On the offensive side, it's good to have a lineup that can score in a hurry, via the home run, rather than one that relies on stringing singles together.
Here's a rundown of the challengers, and how things might look if they can get into the tournament.
It hasn't been that long since the Braves looked like the second best team in the National League. Now they're in a fight just to make it into October. Health is a major concern here. The Bravos are down two starting pitchers, a pretty big problem for a team whose greatest asset has been its rotation.
Maybe more worrisome, though, is a downturn from some apparently healthy pitchers. Derek Lowe has a 6.00 ERA since the start of July, while Craig Kimbrel and Jonny Venters have shown signs of fatigue after being worked hard all year.
On the offensive side, Atlanta can hit the long ball, but it also has a low team on-base percentage. This is a lineup that can get hot and do a lot of damage, but can also be pitched to.
The verdict: It could all come together, but the signs are not very positive.
St. Louis Cardinals:
The opposite of the Braves, the current Cardinals team looks a lot more like one built for October than the one that took the field two months ago. St. Louis has added a power starter in Edwin Jackson. It's upgraded defensively by installing Rafael Furcal at shortstop. It's upgraded the bullpen with a series of moves, and Jason Motte looks dominant in the ninth.
To top it all off, the Cards have gotten healthy, though they're waiting on Matt Holliday's status. The current Cardinals are the team that the front office thought it was assembling back in the winter -- plus Furcal, Jackson and the new relievers, and minus Adam Wainwright and possibly Holliday.
The Cards have a high team OBP and quite a bit of power. Their defense still isn't at the level of some of their competitors, but Furcal has been a major upgrade. They wouldn't be a lock to do anything if they got in, but they'd be a team to watch.
The verdict: A lot would have to go right, but you can definitely see how this team could make a deep run. They just need to get there.
San Francisco Giants:
They're alive! A team that looked completely cooked has roared its way back into both the Wild Card and NL West pictures. The Giants have three games remaining against Arizona, and they're only chasing one team. Either way, though, the question is what happens if they do get in.
And, well, we've seen this movie before. The Giants have the first thing you always look for: the front of their rotation is absolutely top-notch, able to go toe-to-toe with even the mighty Phillies. Their bullpen is deep and effective, even with questions surrounding Brian Wilson. They even match up well on defense, with the fifth-best defensive efficiency rating in the Majors.
The problem is the offense. With no Buster Posey, even the addition of Carlos Beltran has only made this lineup passable. But they didn't have much more than a passable lineup last year, and they won the whole thing. The Giants have their share of injuries, but aside from Posey, most of them shouldn't be too costly in October.
The verdict: They'd almost certainly have the weakest lineup in the playoffs, and they'd still be a team to take very seriously. Nobody wants to see the Giants in a short series.
Boston Red Sox:
Red Sox Nation is in a full-on panic, but remember, with eight games to play, any lead is a significant lead. However, if Boston does manage to make it into the playoffs, there's a very big worry: the Sox are not healthy at all.
They're down three starting pitchers and three guys who are or have been regulars in their lineup -- among others. At their best, the Red Sox are at least arguably the best team in the game. The problem is they're nowhere near their best.
Still, the front of the rotation is imposing, with Josh Beckett and Jon Lester a handful for any lineup. And even a decimated Red Sox lineup is still dangerous. The bullpen has some nice weapons, though it's not as deep and dominant as some.
The verdict: They've done it before, so you'd be foolish to count them out. But just as with the NL front-runner, the team in the lead in the American League won't have an easy go if it gets to the postseason.
Tampa Bay Rays:
Like the Cardinals, they're better now than they've been all year, though in this case it's thanks to some second-half callups. Like the Giants, the front of their starting rotation is seriously potent. And unlike either of them, they're very close to taking the Wild Card lead. Like none of the teams above, there's not a single really essential Ray who is unavailable.
The Rays' bullpen doesn't jump out as far as numbers, but when you start looking at how it actually matches up, you realize it will be a force. The arrival of Matt Moore improves this group significantly, and there's not a manager in the field who is more adept at handling a bullpen than Joe Maddon.
The offense isn't exactly spectacular, and that's a concern. But once again, it's better than the overall numbers look because Desmond Jennings hasn't been around all year. And then there's that defense -- far and away the best defensive efficiency rating in the Major Leagues.
The verdict: If you're a Yankees, Tigers or Rangers fan, you should be rooting very hard against the Rays. They will be a major force if they get in.
Los Angeles Angels of Anaheim:
The Angels are a bit like a Rays Lite. They play the game in a similar way, with a strong top of the rotation, a deep and effective bullpen, a quality defense, a superb manager and a questionable lineup. Also like the Rays, they're healthy.
But they're just not quite as good as the Rays. They're not as good a defensive team, though they're quite strong. Their lineup isn't quite as prolific as the Rays', while playing in a weaker division. The front of their rotation may actually be a bit better, though, and that's no small thing.
So this is a very dangerous October team, for the very same reasons that Tampa Bay is. This would have been hard to imagine as recently as midseason, but out of these three teams, the Red Sox may actually have the worst chance of winning the pennant out of these options.
The verdict: Maybe not quite as dangerous as Tampa Bay, but the mixture is right. This is not a team you want to face in a short series.