This suggests that, much as 2008 was the year that Democratic-leaning districts determined that they could no longer afford to send Republicans to Congress, no matter how moderate, 2010 is the year that the Republican-leaning districts made the inverse decision. It didn’t matter whether the challenger had experience, or if he raised a lot of money. Neither of those variables is statistically significant.
This doesn’t mean that this election was all about the economy. Far from it. As Jon Chait pointed out, a statistical model based only on economic/structural facts suggested that Democrats should lose only about 45 seats. This is only one model and it suggested the worst-case scenario for Democrats; other “structural” models put the number in the 20s and 30s. In other words, the Democrats’ losses were about 20 to 40 seats in excess of what we would expect from the effects of the economy and back-to-back wave elections. Remember, Reagan’s Republicans encountered similar economic headwinds in 1982, and they lost 26 seats, a baker’s dozen of which can be directly chalked up to the intervening redistricting.
Rather, it suggests that voters in swing- and Republican-leaning districts decided that they disliked the Democrats so much that it didn’t matter whether a candidate supported the President’s health care bill or the stimulus. They voted against them anyway.