Bush and Rumsfeld are taking the wrath of the chattering classes on the nose and the mass defection of the willing and supportive. Military punditry posits courses of actions tagged Go short, go big, go long, or get out. All seem to accept the status rotative that destabilizes any effort regardless of intent. Some say that the US military was trained for the wrong war and can’t fight the right one. It is true that Rumsfeld announced on Saddams fall that the Ghost of Vietnam was dead and that the Transformed Light Fantastic had won.
It is true that Transformation wasn't Rumsfeld's idea, and the evil that it has wrought would have visited itself upon either Democratic Presidential candidate had either of them won. There was, and is, a sinister synergistic effect between the Pentagon's union protectionism of Elitist Warriorism and Neo-Conservatism's fetish for privatization. Both don't want Warriors to do un-warrior non-union jobs like logistics, intelligence, civil affairs and military government, psychological operations, or military police.
The Pentagon's penchant for stabilized unit rotation to maintain Warrior unit cohesion has necessitated unstabilized rotation and cohesion in non-union jobs and defeated the attempts of the Warrior class to maintain stability in Iraq and would have done so with the proper ratio between troops and Iraqis. What is a tribute to the quality of the leadership of the troops in the field is the ability to function efficiently with remarkable effectiveness given the chaotic state of the command, control, and support structure in support of the rotating brigades.
The definitive study on psychological war "Cohesion and Disintegration of the Wehrmacht" by Berelson and Janowitz held that as long as the troops' primary group was intact and a basic faith in Germany remained, the troops would fight on. A primary group is rarely larger than a company. The concept of unit rotation for combat units benefits from this principle, but the process of derivative "units" cherry picked from the Guard and Reserve can only be interpreted as an attempt to wreck the reserves. Nice try, but our Guard and Reserve troops have weathered this and have soldiered on with an attendant cost in PTSD.
The disintegration of Iraq can be reversed by reversing the rotation of units and mobilizing the proper command structure for stability operations from the Guard and Reserves as intended by the Congress and all previous planning. In short, go there and come back with their shields or on them. This is war, not a live fire exercise.