Of course, both of those areas have undergone extensive redevelopment, so the population has also changed quite a bit. In the case of the Navy Yard area, development was in some sense pioneered by the stadium, but the big motivating force was displacement of outmoded industrial buildings in response to residential pressure from the north. What local residents there were were mostly displaced by development and thus were not much helped by improved policing or any drops in crime.

The massive development in the Penn Quarter/Gallery Place/Chinatown/Mt. Vernon Square area was driven by changes in the Washington area economy and a shortage of premium office and residential space in the downtown area, and an intersection of Metro lines. It almost certainly would have happened with or without the arena.