One of the things that Boston sports fans are extraordinarily good at, is negativity. We all like to bust Pitino's chops about "the negativity in this town sucks!", but, he had a point. Being a Sox fan for almost 40 years, I'm "bearly" qualified to opine on the team, but, when Sox fans are shown the "silver lining", their first reaction is to look for the grey cloud. 2004 and 2007 softened that a bit, but, we're still always waiting for the other shoe to drop, and expecting it to have dog poop on it when it does. That's just the way "true" Sox fans are, and, often Bruins fans. The Celts and Pats have won just enough, often enough, and recently enough, that fans don't automatically expect the worst (but, they ain't surprised by it none, either).
Getting back to the Sox. Before 2004, it was an annual ritual - which Sox player is gonna be the designated "whipping boy" for the fans, once it becomes apparent that the team was gonna fall short. I remember Bellhorn getting that role, Nomar before the trade (actually, for a while, any and all shortstops were dumped upon), JD Drew, Calvin Shiraldi,..the list goes on. Winning a couple of series tempered that a bit, but, the end of the 2011 season brought it back full force, with "beer-and-chickengate" (which makes me remember "Johnny from BurgerKing").
I don't like this strong tendancy of Boston sports fans to go "nuclear negative" at the first sign of difficulty, but, it's long and well established.
But, I do believe that the way the city reacted to the Marathon bombings reflects the flipside of that same civic personality. Boston is good - real good - at being pi$$ed off. Boston has a chip on its' shoulder, and a defensive edge to its' personality. Kinda a' "Yeah? Well, I'll show you, you bahstud!" mindset. When the bombings occurred, the caring side of the city, both as individuals and as a community, came out. But, so did that defiant quality - this is not a city that blinks when somebody kicks it in the crotch: it gets back up, spits on it's hands, slaps 'em together, and looks for a pitch it can hit the hell out of.