Petraeus's political skills and ability to sell a strategy involving a negotiated settlement offers Obama more flexibility than he has had with McChrystal in command.
Contrary to the generally accepted view that Petraeus mounted a successful counterinsurgency campaign in Iraq, his main accomplishment was to make the first formal accommodation with Sunni insurgents.
Petraeus demonstrated in his command in Iraq a willingness to adjust strategic objectives in light of realities he could not control. He had it made it clear to his staff at the outset that they would make one last effort to show progress, but that he would tell Congress that it was time to withdraw if he found that it was not working.
As commander in Iraq, Petraeus chose staff officers who were sceptics and realists rather than true believers, according to accounts from members of his staff in Iraq. When one aide proposed in a memorandum in the first weeks of his command coming to terms with the Shia insurgents led by Moqtada al Sadr, for example, Petraeus did not dismiss the idea.
That willingness to listen to viewpoints that may not support the existing strategy stands in sharp contrast to McChrystal's command style in Afghanistan. McChrystal has relied heavily on a small circle of friends, mainly from his years as Special Operations Forces (SOF) commander, who have been deeply suspicious of the views of anyone from outside that SOF circle, according to sources who are familiar with the way his inner circle has operated.