I suggest, if you intend to Monday morning quarterback, you get an accurate tape of the game.
Not only that, even had they not simply disbanded on their own accord, from the total lack of command and control exhibited by the IA, throughout the ranks, it might well have been a harder task to first undo all bad training they had before rebuilding it than to simply start afresh with properly motivated volunteers.
There certainly was an army left. Suggest you make a list of all the players in Iraq who would be best prepared to look after the country.