MacChrystal and his band of merry-makers knew they had a journalist with the- they just figured this journalist would be like all the others, that is to say, the truth would be hidden from the public and the falsity conveyed.
Out of the dozens, or possibly hundreds, of 'embedded' journalists in Afghanistan, not one had reported the truth to those of us at home. The possibility of such a thing happening simply did not exist in MacChrystal's brain. He knew all about how to leak and talk to the press to undermine Obama's stated policy goals, he was no babe in the woods when it came to the press- he simply hadn't met a reporter who considered telling the truth more important than maintaining 'access' to the rich and powerful.
Shows how much we know.