the c's are down right now, and likely will be for a few years. note that the poll asks what is your FAVORITE team. at a given moment, the fans are most invested in the teams closest to a championship. bruins had horrific ratings and only fringe appeal for years; they're perennial title contenders now, and they also have their hardcore base to fall back on, which is why they're going pretty well.
sox are pretty self-explanatory.
the NFL, and especially the pats, attract a lot of fake fans. they watch a few games a year and call themselves "the biggest fan" afterwards.
and around draft time every NFL fan acts as if the draft is the greatest event in the world, and as though they know every player in the draft, and as though player X in the 4th round is gong to make a huge difference etc.... but 99% of them are lying, i guarantee you hardly any fans know anything about the left tackle from arizona state, or whatever. i could go on in greater detail about the ignorance of NFL fans, but i won't, it just annoys me for some reason.