Results of a study done by the Brand Keys research consulting agency, known as the "Brand Keys Sports Loyalty Index" have recently been released, naming the five most and five least loyal MLB fan bases (h/t CBS Philly).
From the article:
According to Brand Keys, the Sports Loyalty Index gives an apples-to-apples comparison of the intensity with which fans support the home team vs. corresponding values for the fans in the other teams in the market.
The five most loyal fan bases, according to the report: 1. New York Yankees, 2. Philadelphia Phillies, 3. San Francisco Giants, 4. St. Louis Cardinals and 5. Atlanta Braves.
The five least loyal fan bases according to the report: 30. Houston Astros, 29. Kansas City Royals, 28. Pittsburgh Pirates, 27. Seattle Mariners and 26. New York Mets.
Those were the results of this companies scientific study on fan loyalty, and in turn here are my completely non-scientific, largely opinion-driven rankings on the most and least loyal fan bases in the MLB.