DC Metro Area is 6.4 million, Baltimore 2.8 million, and the census gives them a county in the Eastern Shore. DC media market is also 2x as large. Over 30,000 housing units were permitted in metro DC last year vs. just 6,000 in metro Baltimore. Stadium revenue is much higher at Nats Park than OPACY due to higher ticket and concession prices, reflecting higher income in the region.
When I lived in Fairfax County, there were not many O's fans around. It was a lot of Nats and fans of teams where people grew up. My son's Little League team did that thing where each kid had to say who their favorite player/team was, it was about 60% Nats/40% Red Sox, Yankees Cubs, etc.
Baltimore is not a viable MLB market at this point, the DC metro area is subsidizing its existence, and the demise of cable TV is going to put additional pressure here. The Angelos family can't legislate that people move to Baltimore.