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 26th games:

The rankings from last week are in parenthesizes.

1. (1) Washington Nationals – 4.19

The Nationals have decided to rest up for the playoffs. They have won just five of their last 10, but still sit atop our rankings.

2. (2) New York Yankees – 3.97

In winning eight of their last 10, the Yankees have built a slim lead over the Orioles in the American League East.

3. (T3) Texas Rangers – 3.92

The Athletics continue to put pressure on the Rangers, who lead by three games heading into the final week of the regular season.

4. (T3) Cincinnati Reds – 3.90

The Reds want to play in Cincinnati. They are tied with the Tigers for the best home record (49-31) this season.

5. (7) Tampa Bay Rays – 3.86

The Rays have a +107 run differential this season, while the Orioles are -1. Tampa Bay sits fifth on this list, while Baltimore is tied for fifteenth. That doesn't matter, the Birds will likely make the playoffs while Evan Longoria and Co. watch from home.

6. (6) St. Louis Cardinals – 3.83

The Cardinals know what it's like to take advantage of a collapsing team in the final week of the season. They just need a few wins in their last six contests to grab a Wild Card berth.

7. (5) Detroit Tigers – 3.82

The Tigers and White Sox are in the most important division race of all because the loser isn't going to be good enough to win a Wild Card spot.

8. (8) Los Angeles Angels – 3.70

The Angels are alive, barely. They have to catch the Athletics and both clubs play Seattle and Texas.

9. (9) Atlanta Braves – 3.64

A year after a nightmare in Game 162, the Braves have already punched their ticket.

10. (10) Oakland Athletics – 3.61

Oakland has left the door open for the Angels or Rays to pull off a miracle and grab a Wild Card berth. A poor final week could wash away a season's worth of good feeling.

11. (13) San Francisco Giants – 3.54

12. (11) Arizona Diamondbacks – 3.49

13. (12) Milwaukee Brewers – 3.45

14. (15) Los Angeles Dodgers – 3.40

T15. (14) Chicago White Sox – 3.35

-- (16) Philadelphia Phillies – 3.35

-- (17) Baltimore Orioles – 3.35

18. (18) Pittsburgh Pirates – 3.11

19. (19) San Diego Padres – 3.01

T20. (20) Kansas City Royals – 2.92

-- (21) New York Mets – 2.92

22. (24) Seattle Mariners – 2.87

23. (T22) Miami Marlins – 2.80

24. (T22) Boston Red Sox – 2.78

25. (26) Colorado Rockies – 2.47

26. (25) Toronto Blue Jays – 2.46

27. (27) Minnesota Twins – 2.37

28. (28) Chicago Cubs – 2.33

29. (29) Cleveland Indians – 2.26

30. (30) Houston Astros – 2.07