According to the author of the nonfiction book, The Afghanistan Papers, why did Stanley McChrystal resign from his post with NATO?

McChrystal was the commanding of NATO forces in Afghanistan for the period of June 2009 to June 2010. He resigned this position after a Rolling Stone article profiling him quoted his disrespectful remarks about civilian leaders up the chain of command from him. The article reflected very poor military discipline and ended his career.