For a fascinating read on the role of historians today, check out the latest article from Historians.org.
Historians, I think, have been reasonably well trained in how to read documents and understand documents and deconstruct documentation. Good historians have always done that, traditional or otherwise, in the archives. The archivists certify the authenticity of the document, not the accuracy of its content. However historians have not really understood the necessity of reading the archives itself as a mediator in the accumulation.