Washington and Baltimore are separate communities - separate metro areas (per Census Bureau), separate media markets (per Nielsen and Arbitron), and more. It's not the responsibility of Washington residents to prop up Baltimore businesses (or vice versa).
If Peter Angelos wants more people attending Orioles matches, he needs to stop being such a control freak, get good baseball people into the front office, and build a winner. People aren't going to pay major-league prices for minor-league baseball.