I'm not sure if this post really makes the case, but one of the weirdest ideas floating around is this notion that your emo-prog frenemy on the internet didn't vote in 2010 and therefore Republicans Rule.
Most engaged political junkies vote. The number of people who are engaged political junkies who don't vote is miniscule. It's always fun overestimating the massive power of somewhat annoyed internet liberals on the electorate but, you know, we don't really have much.
It wasn't the Professional Left that lost the House, it was Professional Democrats. The ones that make the big bucks to win these things. In 2012 redistricting played a role. Also, too, professional democrats.