Football fans are not necessarily fickle, Boxer.. but they / we are guilty of becoming tribal in the pursuit of a group identity that otherwise would not exist.
Billy Connolly does a good sketch upon observation of the fans at a match who are unanimous and perfectly choreographed in their singing with nobody on the edge appearing to be struggling with the learning of the song.
How else do you explain away the Postcode gangs? It's the re-appearance of tribalism when it could have long gone!
Let's hope the chelsea-tribe make a lot of aggressive noises at Munich and replace wars with sporting contest!