Douglass at Am Thinker spells out the details. It is rather amusing. Krugman was once an economist, but has been a political hack for years. One quote from the piece:
Paul Krugman has spent his career as a pundit advocating that government bureaucrats and political process replace markets. He knows that there is a large literature that says that this is a bad idea. That literature is transparently relevant to Krugman's only policy proposal. And yet Krugman has not read it...and admits that he has not read it, without embarrassment.
By July, Krugman had lost his "Battle of the Blog." On July 23, Latrina commented, "Who is this Sean from Florida? He takes everything that [the] Professor [says] and shreds it, piece by piece. He shouldn't be allowed to post his comments on this blog since he seems to be winning all the debates. We progressives need to stick together and embellish our talking points without someone from the outside pointing out fallacies in our ideology."