Pesky facts.
Chris Shays held on. Nancy Johnson ran a hard right campaign, when she actually isn't hard right, and lost.
Each district is different of course. There are local issues. Pretending that you run the same candidates in Connecticut that you do in Mississippi is pretty silly. The democrats won actually by putting anti abortion candidates up in purple districts or states. They put up pro second amendment candidates in Western States. They played retail politics well. Those who think that there is some perfect conservative candidate that can be cloned and well represent every one of the 435 districts and 50 states is deluding themselves.