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 Thursday, April 12th 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 the defending-champion Cardinals will maintain such a high rating, while the Red Sox could jump several points over the next week. 1. St. Louis Cardinals - 5.92 The Cardinals have the highest on-base percentage (.371) and slugging percentage (.514) in baseball. They have scored 5.3 runs per game. 2. Texas Rangers - 5.08 The Rangers already have a pair of shutouts in the first week of the season. 3. Detroit Tigers - 4.86 Miguel Cabrera and Prince Fielder have combined for five home runs and 13 RBI thus far. 4. Baltimore Orioles - 4.81 Matt Wieters has started the season off right, hitting .364 with two home runs and an OPS of 1.122. 5. Washington Nationals - 4.77 Washington has the second-lowest team ERA (2.18) and batting average against (.193). 6. Houston Astros - 4.52 7. Kansas City Royals - 4.34 8. New York Mets - 4.20 9. Arizona Diamondbacks - 4.13 10. Philadelphia Phillies - 4.09 11. Los Angeles Dodgers - 4.02 12. New York Yankees - 3.45 13. Toronto Blue Jays - 3.18 14. Tampa Bay Rays - 3.16 15. Chicago White Sox - 3.14 16. Pittsburgh Pirates - 3.10 17. Colorado Rockies - 3.06 18. Chicago Cubs - 2.94 19. Oakland Athletics - 2.83 20. San Diego Padres - 2.49 21. Cincinnati Reds - 2.44 22. Los Angeles Angels - 2.21 23. Seattle Mariners - 1.97 24. Miami Marlins - 1.94 25. Milwaukee Brewers - 1.90 26. Atlanta Braves - 1.79 27. San Francisco Giants - 1.77 28. Cleveland Indians - 1.75 29. Minnesota Twins - 1.34 30. Boston Red Sox - 0.02