From the article: The Rumsfeld Doctrine is: "Just enough troops to lose.".
Funny, but I think it fails to catch the reason that this Doctrine was given credance. The problem is that Rummy thought we could use Afghan tactics to win the peace in Iraq. This administration was suckered by their own success in Afghanistan and failed to correctly apply the lessons.
More than anything, Afghanistan was a Special Ops exercise with proxy forces. We found natural allies in place with the various Northern Alliance and warlord factions. We could use air power to strike with precision and loosen up resistance, and have the Northern Alliance perform the ground operations and set up governance. Bottom line is that we never needed a lot of ground troops in Afghanistan, and we didn't have a large presence locally to give the impression of an occupation force.
Well, Iraq was a completely different war. The Turks made sure they we could not easily link up with the more natural allies of the Kurds in the North. And the Shiites were just bystanders in the process. We've been fighting against both Shiite and Sunni, so neither is particularly on our side. If the administration wasn't so scared of the Shia dominance, they probably would have ignored Sadr and gone straight for the throat of the Sunni's. But that would tip the balance in favor of Iran - something the administration is trying to avoid.
So, we get a force in Iraq that goes in periodically to clean up. Not enuf for a true occupation. Then it expects that by staying out of local governance affairs, that we can let the process naturally gel. Problem is that our presence in Iraq is not in any way similar to Afghanistan.