This is a pretty cool map, but really not that useful.
For example, where I live (in Tampa Bay country) most people have moved from somewhere else and they could care less about the Bucs. It seems there are fans from every team in the league here. And yes, there are some Buc fans -- but they are having trouble filling the stands now. But then again, who in their right mind would sit out in 90 degree weather to watch a football game?? I would rather be cold -- with snow.
And there have always been Cowboy fans all over the country because of the history of the team -- and old habits die hard. I think you only switch alliances when you actually start going to games. That is what happened to me. And after going for 25 -- and still having my season tickets 10 years later (to make money), I am still a die hard.
And another factor, some areas on this map really are college football fans. The NFL comes second.
So bottom line, interesting map, but you have to take it with a grain of salt.