As usual, Paul Krugman calls it like it is.
This is actually a fairly familiar thing from my years as a pundit: the surest way to get branded as not Serious is to figure things out too soon. To be considered credible on politics you have to have considered Bush a great leader, and not realized until Katrina that he was a disaster; to be considered credible on national security you have to have supported the Iraq War, and not realized until 2005 that it was a terrible mistake; to be credible on economics you have to have regarded Greenspan as a great mind, and not become disillusioned until 2007 or maybe 2008.
That's why we have the need of the Freidman Units and that's why we see the Michael O'Hanlons on TV no matter how many times they are wrong.