I believe it was Forbes who did the estimation, who also estimate the value of every team and currently has the Rams last. Given the NFL doesn't open their books, I think a lot of is is estimation, but location, brand, etc all work into it. For example, the Cowboys will always be up there because of brand alone, record or no record. It all factors in, but owning teams, of any sport, in global cities (LA, NYC, London) will always increase value by quite a bit, just due to the location. Similar to why places in LA or NYC are hundreds of thousands of dollars or millions of dollars more for a fraction of the size of a place in Kansas or North Dakota. Location, location, location.