What's wrong with mainstream biblical scholarship is the same thing that was wrong with Christian Naturalism (the field of Darwin's study). Prior to Darwin there was no field of "biology" as we know it today, there was naturalism, which was the theological study of "God's Creation". The study of life on earth was under the purview of the church, which is why Darwin got his degree from a seminary school. But the difference between Darwin and Ehrman is that Darwin recognized the fundamental flaws in the methodologies he was taught, where as Ehrman does not. Ehrman considers his education valid. Ehrman is constantly employing "the criterion of embarrassment" or the "criterion of multiple sources" just as uncritically as Meier or Bauckham or anyone else.