Err it wasn't just a liberal flee the city thing. Cities were becoming increasingly violent, unsafe and inner-city schools were declining. It wasn't a racism thing, it was just a better quality of life outside the cities. Better public transportation didn't help.
The criminal profile was/is completely fucked and didn't make any sense.
I agree that the criminal profile is weird, but I take that to mean that we don't know why they did it, not that they didn't do it. I mean, there's pictures and video of the dude dropping his backpack at the scene of the crime and walking away. And yeah, any random person (especially in boston) could walk around with/drop a backpack, but they fled from the cops WHILE THROWING EXPLOSIVES OUT OF THEIR CAR.