There are a couple of interesting things to note. First, even before the election there were essentially no centrist Republicans in the House. In the three bars [refers to a chart on his site] closest to the center-right, there were a grand total of three Republican incumbents. So there were really no centrist Republicans to target.
Second, the Republican losses were pretty evenly spread. The absolute most conservative Republicans all survived, which isn't surprising since they generally come from the absolute most conservative districts, but aside from that the losses came from across the spectrum of the Republican caucus. When you do the arithmetic, it turns out that the Republicans who kept their seats were slightly more conservative than those who lost their seats, and the end result is that the Republican caucus, which was already far more skewed to the right than the Democratic caucus was to the left, is now skewed even more to the right. But only slightly.
I'm a very lucky person with every allergy known to man but still happy to be enjoying a wonderful life living in the best place in the world!