The large shifting of seats in the US House of Representatives from red to blue may need little more explanation than this: in arguably the worst economic conditions since the Great Depression, the country voted arguably the largest backlash against the party in power since the Great Depression.
I suspect that, once you get beyond the partisans and ideologues, the folks we call "swing voters" took a pretty intuitive and reasonable view of things: they don't blame Obama and the Democrats for causing the recession, and they suspect that actions taken by Obama and the Democrats have kept things from being much worse, but things aren't good, which probably means that Obama and the Democrats don't have the answers to make things good.
It's like having a home-town team that's had back-to-back sub-.500 seasons. Diehard fans think they know exactly what should or shouldn't be done. But the casual fan just thinks that the current team isn't getting the job done, and wants to see some changes made to give him hope that next year will be better.
Mid-term congressional elections, which offer a chance to change one member of one piece of the federal government, offer an easy, relatively harmless way for those voters to express that -- and that's not by accident.
When the framers met to hash out the Constitution, one of their conundrums was how to satisfy their ideological imperative of resting ultimate sovereign authority with "the people," when in their opinion those people (even limited to those who they envisioned as eligible to vote), were by and large uneducated, unsophisticated, narrow-minded, short-sighted, and selfish.
So they took one branch of government -- the judiciary -- and they removed it from direct democracy by having its members chosen by the President and confirmed by the Senate.
They took a second branch -- the executive -- and removed it from direct democracy by having the people select "electors," who (as they envisioned it) would independently select a President, who would then appoint the remainder of the executive offices with Senate confirmation.
In the third branch, they took the more powerful upper chamber and removed it from direct democracy by having the elected state governments appoint Senators.
And then, after much debate, they decided to give "the people" direct control over the selection, and retention, of the less-powerful half of one-third of the government. Yes, the people's fickle whims and desires would probably whip the House of Representatives back and forth, in one direction and another, but the potential damage to the long-term governance of the nation would be limited.
(Of course, since then we have vastly revised our conception of representative democracy, and much of this works very differently today.)
So, yes, the country (in very large turnout numbers) seems to have chosen one direction to steer the country out of its troubles, and two years later reversed course in an entirely different direction. From Pelosi to Boehner in two years. Whichever side you think is right, it does seem to kind of validate the Framers' worst fears of the fickle electorate. But it also, I think, validates their belief in meaningful sovereign authority of the people. And, I would argue, their wisdom in isolating the amount of damage those people can do with that authority.