And what of 2010's redistricting gerrymanders? Last I heard Ohio's new maps are 12-4 Republican/Democrat. I think Pennsylvania was pretty bad too.
They are horrible. Indiana is even worse. The Indiana state legislature set up the state so that it has two D+20 (Cook PVI) districts and seven R+5 districts.
But here is the trouble for Republicans: extremists lose in moderate districts. If the Democrats had elected and set up nominations of a bunch of political clones of Charlie Rangell (well suited to a D+41 like his district) in D+4 districts, then moderate Republicans could likely defeat a bunch of those politicians. Congressional Representatives cannot change the political culture of their districts fast enough, raise enough money for campaigns that flood the opposition into oblivion, or do first-rate constituent service well enough to transform their districts into the sort that go for someone on the political fringe. In such a case, Republicans running as moderates -- perhaps even taking stances different from those of their Parties -- would run against Hard Left pols and win an election or two.
On the other side a Republican in one of the two R+29 districts (TX-13, a district containing Wichita Falls and Amarillo) and AL-06 which contains a large chunk of Alabama that nearly surrounds Birmingham but excludes it and is 88% white in a state only 68% white), a Republican incumbent can get away with a lot. Mac Thornberry (TX-13) ran unopposed in 2010; Spencer Bachus (AL-06) is one of the biggest players in a tolerated inside-trading scheme. (Mavens of good government: if you want few political scandals involving elected Representatives, then do not create D+15 and R+15 districts).
The 2010 election did not bring Republican 'moderates' to the fore. Such might have entrenched themselves quickly enough. Instead the Tea Party types who acted as if they had no concern about getting re-elected or were assured of re-election and voted as if they were in R+30 districts.
To be sure the fresh Congressional Representatives have not gotten entrenched deeply enough to abuse power -- but they have gone into political lockstep. They will get huge money thrown at their campaigns, but that won't consistently be enough. They won with depressed turnout and well-concealed agendas; the voter turnout in a Presidential election usually increases, and Republicans with Hard Right voting records in moderate districts are going to have difficulties in defeating those that their current Hard Right representatives defeated in 2010.
For an analogy in physics try "damped harmonic oscillation". Don't worry about the math.http://www.youtube.com/watch?v=C6idxyQPbiw&feature=related