I may be ignorant, but doesn't it take a lot of statistical analysis to do attacks like this? The point being not that the NSA cannot do it, but that they have

I may be ignorant, but doesn't it take a lot of statistical analysis to do attacks like this? The point being not that the NSA cannot do it, but that they have to be specifically targeting you to pull it off. Unless they know what's going through the wire, how will they know to target you?