I love talking about attendance. No really, I do. It the kind of tangental topic that can be bandied about easily between opposing parties because honestly - we don't know why things are the way they are and there are a lot of facts that can be thrown around without exactly knowing the magnitude of their effect. Schools still in! Weather! Economy!
Boz tackles the current strong attendance of Baltimore and DC in a weird way. He gloats. He compares this area to other areas with two teams that currently have lower attendance figures. (Unfairly, I might add since those areas have a total of 0 winning teams. Then he excuses the fact that SF/Oak outdraws DC/Balt by saying those teams are powerhouses but (1) No SF isn't (2) Oakland has a notoriously awful stadium.) He says MLB told him baseball wouldn't work here. He acts like he was the only one who said baseball wouldn't work in Florida (If I recall correctly that was an idea held by roughly 132% of all people)
Is he right? Is the DC/Baltimore area a sleeping giant when it comes to baseball?
The easy thing to say, and something generally verified by looking at attendance figures is that attendance follows record. You win you draw fans. You lose you don't. The effect is somewhat staggered, which is why a 98 win Nats team, after a long stretch of bad baseball, couldn't break the top half of the NL in attendance, and a 73 win Phillies team, after a long stretch of good baseball, can be 4th. You also need consistency - one good season followed by a downturn (or vice versa) will simply dent attendance trends. The Nats and O's are working on their 3rd seasons of above .500 ball and both are fighting for 1st place in their division. Logic tells you fans will come to see that.
So the area is normal, right? Well Boz sets his own "this is when attendance goes up" rules which make the area look as good as he can make it. He states that winning a playoff series drives attendance up. Since the Nats and O's haven't done that - their rise in attendance is more impressive. This is a harder thing to prove. What team has three years of good baseball and fails to win a series? But baseball has a lot of teams and a long history so let's see what we can find relatively recently.
2006-2008 Blue Jays : The Blue Jays led the league in attendance in the early 90s then the Jays slowly fell to mediocrity with average years puncutated by decent ones and poor ones. After a low point of 67 wins they bottomed out at 11th in 2005, despite a record near .500. From 2006-2008 the Blue Jays put up 3 consecutive 83+ win seasons without making the playoffs. Attendance by the last season? 6th.
2000-2004 White Sox : Prior to winning it all in 2005 the White Sox put up 4 consecutive winning seasons (well non-losing seasons - there's an 81-81 in there). The attendance in '99 was 13th. In 2004 was 8th. It's a bumpy rise because the Sox' best year was 2000 but it's a rise.
1999-2001 A's : The mid 90s A's were bad after dominating the late 80s time frame. By 1999 though they were back in business. They won 87, 91, 102 games and the attendance increased from 13th in 1998 to 7th in 2001.
2009-2011 Braves : But the Braves were always good! Nope. After losing 4 consecutive DSs the Braves missed the playoffs from 2006-2009, so by the time they put up these three winning years it had been almost a decade since they won a series. Far enough away? I think so. Anyway. 2008 10th. 2011 8th. (the Braves actually haven't drawn well since the newness of Turner Field wore off)
1997-1999 Mets : Mets really bottomed out from late 80s success and... I'm getting tired, let's wrap this up. 1996 12th (out of 14) 1999 7th.
That's about all I could find. I skipped a couple teams who might be draws in of themselves regardless of record and a couple other teams might have qualified but the time frame overlapped with a new stadium being introduced making attendance figures fuzzy to interpret. It's actually kind of rare to put up three above .500 seasons in a row and not win a series in the first two years, at least since the WC was introduced. Looking at the small data we see here - we see that DC/Balt is not special*. When you win consistently, division series win or not, attendance goes up.
(*In fact I think a stronger case could be made that DC is actually still kind of disappointing, given the quality of the team and the population to draw from. But I say give the fanbase another 10 years to build before judging them as if they are on an even playing field)