By Andrew Perna 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 Friday, April 20th games: The rankings from last week are in parenthesizes. The rankings and Opsera rating for each team will be volatile this month as the data increases. After 162 games in 2011, the Rangers had the highest rating (4.21) and the Twins the lowest (2.08). It is doubtful that Texas will maintain such a high rating, while Boston could jump several points over the next week. 1. (2) Texas Rangers - 6.43 The Braves have scored more runs, but the Rangers have the highest OPS (.881) in all of baseball. 2. (1) St. Louis Cardinals - 5.48 St. Louis has the second-highest OPS and the fifth-best ERA in the game. 3. (11) Los Angeles Dodgers - 4.41 Matt Kemp has made the offense very explosive. 4. (5) Washington Nationals - 4.33 A tremendous pitching staff has made up for a below-average offense. 5. (12) New York Yankees - 4.32 The Yankees have been kept afloat by their offense as their starting rotation has been middling. 6. (10) Philadelphia Phillies - 3.97 The Phillies have, as expected, gotten tremendous efforts from their starters. The offense, not so much. 7. (4) Baltimore Orioles - 3.93 Buck Showalter has his team playing well so far, but it is still very early. T8. (15) Chicago White Sox - 3.92 -- (26) Atlanta Braves - 3.92 10. (3) Detroit Tigers - 3.83 11. (24) Miami Marlins - 3.60 12. (8) New York Mets - 3.56 13. (17) Colorado Rockies - 3.51 14. (27) San Francisco Giants - 3.47 15. (6) Houston Astros - 3.43 16. (19). Oakland Athletics - 3.08 17. (13) Toronto Blue Jays - 2.87 18. (7) Kansas City Royals - 2.83 19. (28) Cleveland Indians - 2.82 20. (9) Arizona Diamondbacks - 2.70 21. (16) Pittsburgh Pirates - 2.61 22. (23) Seattle Mariners - 2.53 23. (22) Los Angeles Angels - 2.49 24. (20) San Diego Padres - 2.48 25. (21) Cincinnati Reds - 2.45 26. (14) Tampa Bay Rays - 2.30 27. (25) Milwaukee Brewers - 2.03 28. (29) Minnesota Twins - 1.96 29. (30) Boston Red Sox - 1.52 30. (18) Chicago Cubs - 0.91