I don't entirely agree with Murphy. I'm for withdrawal, starting soon, but not on a fixed timeline. The situation is just too fluid and we shouldn't be giving time parameters to the enemy. But that's a minor detail.
If we had a president who was competent and actually wanted to bring troops home, this position would be fine. But we don't. George Bush is president, and he is incompetent, and the people he surrounds himself with are, for the most part, incompetent. More than that, he has decided that leaving Iraq is equivalent to surrendering to "the enemy," whoever the hell that is (there's an insurgency and a few different civil wars and another one probably on the way). So the choice isn't between Pundit Pony Plan and George Bush's Plan, the choice is between forcing George Bush to leave any way you can or continuing to let George Bush fuck things up.
We don't all get to micromanage the Iraq war - not me, not Joe Klein, not Nancy Pelosi. The choices are, basically, staying or leaving. Maybe Pony Plan X is superior to that option, but Pony Plan X generally involves wishing that competent people who wanted to leave Iraq were going to do that in a sensible way. That just isn't really an option.