The New Deal and the Depression: Interesting stuff. I agree that the NIRA might have raised the structural rate of unemployment - but the economy got nowhere near the structural level of unemployment during the NIRA period, so what difference could that have made?
What really puzzles me, though, is the assertion that wage and price rigidity created by the New Deal aborted the natural recovery process. Through what channel could price flexibility have helped? The US spent most of the 30s pretty much up against the zero bound, with interest rates well below 1 percent. A fall in the price level would have had the same effect as an increase in the monetary base - that is, no effect at all - except for the slight wealth effect of rising real balances. And even this slight effect could easily have been outweighed by debt deflation.
You just have to bear in mind that this was, um, the Great Depression - normal rules about monetary policy did not apply. And the same goes for any possible role of price flexibility.
In support, Brad adds Chapter 19 from Keynes The General Theory of Employment, Interest and Money:
[Update: See also PGL at Angry Bear.]
[Update: See Robert Waldmann's comments as well.]