I inferred what you were suggesting about Detroit's economy in your initial 5+ word post. Your subsequent post criticizing Detroit's economy confirmed what I inferred. Therefore, my conclusion about your logic was right on. The Detroit economy has been pretty bad over the last decade, yet when the teams win, they sell and they make money. When the teams are bad, they don't sell and they don't make money.
The economy has some effect, but it's not the main reason a sports team loses money in Detroit. Not a difficult concept to grasp... for most people.