We're now into September, which means three things: people overplaying a perfectly good Green Day song to the point of nausea, I'm watching Friday Night Lights on repeat, hoping Mike Winchell will finally lower his center of gravity to get across the goal line, and we're approaching the best baseball of the entire year. In case you hadn't guessed, we'll be focusing (mostly) on the third of those certainties.

With only a month left in the season, the title of post-season favorite is still largely up for grabs. These power rankings can show which teams are primed to dominate when September ends. If you want to see the entire rankings from 1-30, you can click here.

The rankings are based on numberFire's nERD stat. Outside of just sounding like a sweet statistic, it also measures the expected run differential of a team if they were to play a league-average team. Thus, a team with a 1.00 nERD would be expected to beat a team with a -2.00 nERD by three runs at a neutral site. You can read more on that by clicking here. Considering we've had a change at the top, let's just dive right into the top five.

1. Oakland Athletics

nERD: 1.00 | Playoff Chances: 99.3% | World Series Chances: 10.2% | Previous Ranking: 1

In our rankings two weeks ago, the A's had a 17.1 percent chance at winning the World Series. In just 14 days, they lost almost seven percentage points. That takes some epic suckage, and the A's achieved exactly that.

Over their last 21 games, Oakland has won only seven. They have also only scored more than three runs seven times over that stretch. Not-so-coincidentally, they are 5-2 in those games. Enter Adam Dunn.

As numberFire's John Stolnis wrote yesterday, Dunn will not be the savior the A's need. However, within that article, John was able to draw an interesting parallel between Dunn's offensive numbers (0.80 nERD) and those of Yoenis Cespedes (0.79 nERD), whom the team traded at the deadline. At this point, the team will take what it can get.

2. Los Angeles Angels

nERD: 0.97 | Playoff Chances: 99.9% | World Series Chances: 16.6% | Previous Ranking: 2

Any time you can force your division rival to have an extended, closed-door team meeting, you done did something right. That's what the Angels accomplished this weekend by out-scoring the A's 18-4 in a four-game sweep. Thus, prior to last night, the Angels had removed the A's from the top of the power rankings. Alas, maybe next week.

The Angels have already won six in a row, and over the next 13 games, their opponents' composite record is 764-1020. Over that stretch, only the Indians are on pace to lose fewer than 90 games, and they only play them once. That 4.5 game lead in the West just looks prettier and prettier.

The scary thing for the Angels, not now but in October, will obviously be pitching. With Garrett Richards going down with his knee injury, the Angels no longer have any pitchers worth more than two wins above replacement. Matt Shoemaker has been iller than the illest since the Richards injury (21.2 innings, eight hits, zero runs, three walks, 22 strikeouts!), but the rest of the rotation needs to follow his blazing path if the Angels want to win it all.

3. Los Angeles Dodgers

nERD: 0.78 | Playoff Chances: 99.0% | World Series Chances: 17.0% | Previous Ranking: 3

Between the Dodgers and the Angels, the city of Los Angeles has a 33.6 percent chance at winning the World Series. Think it's a good time to be a Cali native? Well, it probably always is, but you know what I mean.

Even with these high playoff and championship odds, there are more than a few individuals on the team that are ecstatic to turn the calendar to September. August went all dementor-y on the Dodgers and sucked the production right out of some of their best players.

In the month of August, Kevin Correia had a higher offensive plus defensive fWAR than Yasiel Puig, Matt Kemp, Dee Gordon, A.J. Ellis and Andre Ethier. No bueno. Thankfully, Adrian Gonzalez and Justin Turner were out slangin' hits, so the team only lost a half game to the Giants, but they need to kick this puppy into gear to keep that lead in the West.

4. Washington Nationals

nERD: 0.58 | Playoff Chances: 99.4% | World Series Odds: 13.9% | Previous Ranking: 5

Entering play last night, the Nats were plopped in sixth place in the power rankings. Then, they went on the road, knocked off those mighty Dodgers, and voila. Here they are in the top four.

Even after their blech three-game sweep at the hands of the Phillies, the Nats are still a stupidly talented team. Among National League teams, Washington ranks first in ERA, fielding-independent pitching, and walks-per-nine. I think that'll get the job done. Their starters are averaging just 2.02 walks-per-nine, the second-lowest in the league behind the Yankees. This combines with their opportunistic offense to make the Nats dangerous now and for the rest of the season, thus the 13.9 percent chance at winning it all.

What's even better for the Nats? It's looking like Bryce Harper may be starting to heat up. Over the last four games (yeah, yeah, yeah, small sample size boo hoo), Harper has blasted three mammo's and has a pair of three-hit games. If you add an effective Harper to the rest of that line-up, it's finna get crazy, homies.

5. San Francisco Giants

nERD: 0.55 | Playoff Chances: 87.9% | World Series Chances: 7.5% | Previous Ranking: Not Ranked

As I mentioned in today's "Burning Question", the Giants have been a darn good baseball team outside of that wretched stretch in June and July. Their .623 winning percentage outside of that skid would be by far the best in the league. Now, they're back to early-season form.

Their loss last night (to the Rockies, of all teams) ended a six-game winning streak over which they outscored opponents 42-11. Madison Bumgarner is a machine out to destroy the happiness of all opposing teams. Opponents are hitting .181/.211/.297 off of Bumgarner in the second half of the season, helping explain his 9.98 strikeouts-per-nine, 0.98 walks-per-nine (a 10.14 strikeout-to-walk ratio!) and his 1.97 ERA. How Clayton-Kershaw-y of him. That, when coupled with the ageless Tim Hudson and Ryan Vogelsong and the re-surgent Jake Peavy will help. This is a World-Series-caliber team when they are clicking. When they aren't, though... baby, it's ugly.