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.  

All statistics are through Sunday, June 1.

Rankings from last week are in parenthesizes.

1. (1) Oakland Athletics – 4.64

The Giants have the best record in baseball, but the Athletics have an amazing +115 run differential.

2. (2) San Francisco Giants – 4.13

If things continue this way, San Francisco should look to add offense for the playoff run.

3. (7) Milwaukee Brewers – 3.88

Milwaukee is one of only three teams -- including Oakland and the L.A. Dodgers -- that rank in the top ten in both ERA and OPS.

4. (4) Los Angeles Dodgers – 3.87

Yasiel Puig is hitting .347/.437/.618 with 11 home runs and 40 RBIs in 52 games.

5. (5) Atlanta Braves – 3.85

Justin Upton is having his best season at age 26 -- .301/.380/.575.

6. (11) Washington Nationals – 3.83

7. (12) Toronto Blue Jays – 3.79

8. (3) Colorado Rockies – 3.77

9. (T9) Miami Marlins – 3.62

10. (8) Detroit Tigers – 3.57

11. (6) Los Angeles Angels – 3.55

12. (T9) St. Louis Cardinals – 3.49

13. (21) Boston Red Sox – 3.33

14. (15) Cincinnati Reds – 3.28

T15. (13) New York Yankees – 3.17

T15. (T18) Cleveland Indians – 3.17

17. (16) San Diego Padres – 3.15

18. (14) Pittsburgh Pirates – 3.08

19. (20) Seattle Mariners – 3.07

20. (T18) Baltimore Orioles – 3.00

21. (26) New York Mets – 2.97

22. (24) Philadelphia Phillies – 2.89

23. (22) Texas Rangers – 2.88

24. (17) Chicago Cubs – 2.85

25. (27) Chicago White Sox – 2.80

26. (28) Houston Astros – 2.71

27. (23) Kansas City Royals – 2.65

28. (25) Tampa Bay Rays – 2.62

29. (30) Minnesota Twins – 2.49

30. (29) Arizona Diamondbacks – 2.46

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