Brendan Nyhan previews the vapid post-election analysis to come:

It's long been obvious that Obama's political standing would decline as a result of the poor economy and the passage of time. Similarly, substantial Democratic losses in the House were always likely given the large number of seats the party had to defend in a midterm election in which it controls the presidency. The continued weakness of the economy subsequently appears to have enhanced the Republican advantage, helping to produce tomorrow's pro-GOP wave.

Instead of focusing on these structural factors, journalists and other political figures have constructed a staggering number of ad hoc claims about messaging, tactics, etc. to "explain" what has happened to Obama and the Democrats:
-Obama's message is not populist, thematic, simple, and/or comprehensive enough;
-Obama failed to "connect" with voters (in part because he often uses a Teleprompter);
-Obama has an "empathy deficit";
-Obama has no chief economic spokesperson, lacks sufficient political and policy integration, has failed to distance himself from Congressional Democrats, and needs to delegate more to his cabinet on domestic policy;
-Obama is seen as an elitist;
-Obama is too dependent on a small number of senior advisers;
-Obama failed to establish a rationale for his agenda during the campaign;
-Obama is a "legislative president" who "is not a great pitchman for his policies";
-Obama is "too articulate";
-Obama "forfeited control of the narrative" and has failed to offer a "theory of the case" or "The Sentence";
-Obama dislikes politicking, lacks intensity in campaigning, and shows indifference on the stump;
-Obama is unlucky and "Americans get nervous when they have a snakebit president";
-Obama was too liberal (see also here);
-Obama was not liberal enough and should have shown more "resolve";
-Obama sounds too pessimistic;
-Obama has not defined himself and Americans don't know who he is.

Some of these factors may play a role on the margin (particularly the public's view of Obama and the Democrats as too liberal), but the effects are likely to be relatively small and should be judged against an appropriate structural baseline rather than the implausible counterfactual that Democrats would be riding to victory if they had only used tactic X. The reality is that political tactics tend to work when the fundamentals are favorable and fail when they're not. That's why even Ronald Reagan and Bill Clinton couldn't save their parties from significant midterm losses in 1982 and 1994. Why would we expect Obama to succeed where they failed?

He even has a handy bingo game: