They did a good job of fighting a defensive battle asymetrically against a force that played by rules. ISIS ain't that. It is a highly mobile force willing to do anything to take land and is highly proficient at both conventional and non-conventional tactics. They only seem to fail when presented with advanced weaponry and more skilled forces. Sadr has neither. Sadr's not in a position to go into offensive warfare and is limited only in defending his territories which helps greater Iraq very little.