Well if animal welfare is the metric being used, then the point still stands about the facilities being separate. The animal welfare at the aquarium doesn't have any impact on the animal welfare at the zoo, and vice versa. The same thing would also apply to WCS, San Diego, Zoo New England, Sea World, or anywhere else with two or more gates. Furthermore, I highly doubt an only animal welfare based methodology was used, as doing so, whether in the '80s or today, would not yield only large zoos at the top of the list, as the Parade ranking does. In reality, the zoos with the best animal welfare does include some big zoos, but also some much smaller zoos as well- which is not something displayed in the ranking, hence there must be additional factors at play, whether that be name recognition, size, animal collection, visitor experience, or what have you.