After leaving almost 10,000 empty seats in its Champions League game against Roma last September, the professional football team in Manchester City chose to offer a buy-one-get-one-free deal on tickets at its October match against CSKA Moscow. ("Football" here is meant in the European sense, a game most Americans call "soccer", which in the fall of 2016 may be the only professional football played in St. Louis. Go Ambush!) The promotion was a success in that City went on to sell out its match against CSKA. The buy-one-get-one-free deal, however, drew the derision of fans of City's rival ...