Along Phil's line, Americans aren't as easily pigeon-holed (narrowly defined) as the rest of the world would like.
Some will root for the home guys; some will root for the underdogs; some will root for guys who wear their emotions on their sleeves; some will only root for unemotional players. And some like watching those who play with a flair and excellence above that of anyone they've ever seen - thus the Fed fans.
Contrarian behavior is encouraged in the US - it leads to a lot of the new inventions - e.g. 'thinking outside the box' to use some MBA-speak.