I think you underestimate the power of the red sox brand. I don't disagree that football is #1. However, there are thousands if not millions of homes in the New England area that won't watch football, that are religiously tuned to NESN on a mid summer, mid week game that us football fans could care less about. You know the game, too. It's some kid up from Pawtucket making a spot start because the #5 guy has a blister vs. Kansas City's #4 starter. Mid week, mid summer, on a night when you're sitting on the deck drinking brews. You call your mum up, and she's got the game on. She's got aunt Ethel visiting, and they are breaking down the #5 KC hitter's stance. Then aunt Ethel comes up with how the guy is a philandering pig, and that's why his 0-whatever vs. this kid from the Pawsox that no one's heard of.
short version: is generational. More blue hairs watch the sox than the 30 something male demographic.