OVER EXPOSED His credentials as a Boston sports nut are well established, so it's no surprise Mike Schuster -- Patriots Fan of the Year, 1999 -- shows up in ''Fever Pitch." (He's the guy wearing the inflatable baseball on his head at the concessions stand.) We weren't prepared, however, for his performance at the ''Fever Pitch" red-carpet rally at Fenway. As Jimmy Fallon was leaving the field, Schuster leaned over the dugout and lifted his shirt, revealing the ''Fever Pitch" logo painted on his ample tummy. ''I used high-quality theater paint," Schuster told us. ''I figured if it's good enough for actors performing under hot theater lights, it's good enough for my big fat beer belly." Good thinking. To his credit, Fallon, who actually mentioned Schuster on an episode of ''Dr. Phil," did not run away at the sight of Schuster's bare midriff.