By Christopher Reina The Opsera is a statistic I created in order to objectively rank teams by how well they hit (OPS) and pitch (ERA). In order to determine a team's Opsera, I take their OPS, multiply that number by 10 to move the decimal point over one place to the right and then subtract the team's ERA from that number. After the third week of play, we have our fourth different leader in Opsera, with the Cardinals joining the Phillies (Week 1), Yankees (Week 2) and Giants (Week 3). Given the fact that Tampa Bay has the best record in the MLB and the greatest run differential, it would not be unexpected to see the Rays ranked first next week.

1. St. Louis Cardinals: 5.11
2. San Francisco Giants: 4.97
3. Tampa Bay Rays: 4.72
4. New York Yankees: 4.67
5. San Diego Padres: 4.39
6. Minnesota Twins: 4.35
7. Chicago Cubs: 3.98
8. Detroit Tigers: 3.90
9. Colorado Rockies: 3.87
10. Philadelphia Phillies: 3.69
11. New York Mets: 3.42
12. Texas Rangers: 3.32
13. Toronto Blue Jays: 3.30
14. Los Angeles Dodgers: 3.29
15. Florida Marlins: 3.22
16. Seattle Mariners: 3.16
17. Boston Red Sox: 2.93
18. Atlanta Braves: 2.90
19. Oakland Athletics: 2.90
20. Milwaukee Brewers: 2.86
21. Cleveland Indians: 2.70
22. Washington Nationals: 2.49
23. Los Angeles Angels: 2.48
24. Kansas City Royals: 2.44
25. Arizona Diamondbacks: 2.35
26. Baltimore Orioles: 2.35
27. Chicago White Sox: 2.11
28. Houston Astros: 1.83
29. Cincinnati Reds: 1.49
30. Pittsburgh Pirates: -0.06
Chris Reina is the executive editor of RealGM. Follow him on Twitter at http://twitter.com/cr_reina.