I think the key to understanding why some of the teams havent had to change logo is they were not a transplant team in the modern day. They have a base who could care less whether they had a pic of Bidwill naked on it, they have a history, we were not lucky enough to have that. And in a city made up of people from every city you have to compete some how to earn thier loyalty. obviously winning will do that, but I think that the a new slightly different look is a good way to shake the old image.. And as for teams that have had a huge history of winning, eagles, broncos ect, they have made drastic changes to thier logos..