The Opsera is a statistic RealGM Executive Editor Chris Reina created in order to objectively rank teams by how well they hit (OPS) and pitch (ERA). 

In order to determine the Opsera rating for each, we take their OPS, multiply that number by 10 to move the decimal point over one place to the right and then subtract their ERA from that number.  

Below are the rankings through the Wednesday, September 19th games:

The rankings from last month are in parenthesizes.

1. (2) Washington Nationals – 4.19

They own baseball's best winning percentage (.608) and the highest run differential (+129) in the game this season.

2. (1) New York Yankees – 3.96

The Orioles aren't making it easy on the Bombers, who still aren't a lock to make the postseason with two weeks left in the regular season.

3. (3) Cincinnati Reds – 3.95

The best team no one is talking about? The Reds have the biggest edge of any division leader and they are tied with the Rangers for the most home wins (47).

4. (4) Texas Rangers – 3.95

The 755 runs they've scored are far-and-away the highest total in baseball. The Angels, who have played one more game, have the second-highest total at 711.

5. (T6) Detroit Tigers – 3.81

Jim Leyland's crew has a better chance at surpassing the first-place White Sox, two games back, than grabbing a Wild Card berth, five games back.

6. (5) St. Louis Cardinals – 3.79

After slumping, the Cardinals have won three-straight but still have teams hot on their tail for the second NL Wild Card. The Dodgers, Brewers, Phillies, Pirates and Diamondbacks are all within less than five games.

7. (T6) Tampa Bay Rays – 3.72

With just three wins in their last 10 games, the Rays have fallen 5.5 games back in the Wild Card chase.

8. (10) Los Angeles Angels – 3.67

The 2012 season has been a disappointment thus far, but anything can happen if Albert Pujols & Co. just get themselves into the playoffs.

9. (8) Atlanta Braves – 3.63

The Braves have more wins than all but one AL team, but they'll have to settle for a Wild Card as they share the NL East with the Nationals.

10. (9) Oakland Athletics – 3.55

They traded away a good chuck of their pitching over the winter, but Oakland still has the fifth-lowest ERA (3.50) in baseball this season.

11. (12) Arizona Diamondbacks – 3.50

12. (16) Milwaukee Brewers – 3.49

13. (11) San Francisco Giants – 3.47

14. (13) Chicago White Sox – 3.40

15. (14) Los Angeles Dodgers – 3.39

16. (18) Philadelphia Phillies – 3.32

17. (19) Baltimore Orioles – 3.26

18. (15) Pittsburgh Pirates – 3.21

19. (20) San Diego Padres – 3.05

20. (22) Kansas City Royals – 2.98

21. (21) New York Mets – 2.94

22. (17) Boston Red Sox – 2.84

23. (24) Miami Marlins – 2.84

24. (23) Seattle Mariners – 2.81

25. (25) Toronto Blue Jays – 2.60

26. (26) Colorado Rockies – 2.46

27. (27) Minnesota Twins – 2.41

28. (28) Chicago Cubs – 2.38

29. (29) Cleveland Indians – 2.17

30. (30) Houston Astros – 2.04