This is worth reading. "Petraeus's experience over the past decade shows that generals are not immune to the strain. They get used up, too," writes Greg Jaffe. I have heard Petraeus' tour in Afghanistan referred to as his "fat Elvis" period, an unkind way of saying that he was tired and not on his A-game there.
I suspect that in Iraq, Petraeus tried to work with local factors as points of leverage, while in Afghanistan, his campaign against corruption worked against local factors. But I don't know the Afghan war well enough to assemble the evidence for that hunch. Can anyone enlighten me on this?
Thomas E. Ricks covered the U.S. military for the Washington Post from 2000 through 2008.