Two years ago Republicans were excited about the GOP wave that gave us a majority in the House of Representatives, and replaced the dreaded Nancy Pelosi with John Boehner as Speaker. Now, two years later, we're down because we've just had a bad election, at the Presidential and senatorial levels, if not at the House or Gubernatorial levels.
I don't believe the demographics of the electorate changed much in two years. The difference this time was an enormously expensive effort to identify and chivvy to the polls every last Dem voter. Probably anytime such efforts are made, Dems are likely to win because there are more of 'em.
What a difference two years can make.