some teams have made their seating capacity smaller, like the Marlins, and teams like the Red Sox and Cubs can only fit but so much in their ballparks. It looked much worse when baseball and football teams shared stadiums because when the football team ain't there, you gotta tarp so much of the stadium, like in Oakland.
and make no mistake. The Yankees were an insanely major draw for about 8 years or so (in that they'd sell out every seat and draw 3 mil a year). Even during the last dynasty, fans were too scared to come to Yankee Stadium, especially during the week