There are definitely people who "love" teams/players without actually knowing anything about them or caring enough to do any research to make sure they write them well. I probably know more about the 4th liners on my team than I do my favorite star from a different one ... But if I was going to write, say, PK Subban (a player not-on-my-team whom I enjoy), I'd research him, and if the Habs or the Preds were important to the story, I'd look for info on them/appeal to meme for resources, do my very best, etc.

But I also write for a rare team and have seen my faves destroyed in fic, and I wouldn't want to do that to other people!