Fine job based on what? The increased secretarian violence throughout 2006? Even the White House admitted operation TF had failed.
Rumsfeld had a great vision for the military. He didn't have one for the war.
I don't know what was his fault and what wasn't. But when things aren't going well, you need to change things, and sometimes that means key personnel.
I thinks it's very easy to scapegoat Rummy. But remember, he didn't send the army home or fire the government. That was the State Department. When you send an army home with guns and no way to feed their family, you've got to expect trouble.