The winner is the least screwed up
Back in the height of the Cold War I served three years in Germany in 155mm and 8-inch artillery units. Across the Inner German Border, separating West and East Germany, lay the huge and feared Group of Soviet Forces, Germany. In terms of numbers, we were soundly outnumbered and outgunned, but the Sovskies never invaded and eventually became tame Russkies who went home.

Why did they never invade? I pondered the question for years before I got the answer.

One of the things I learned about the Soviet military was that it was riven with corruption from top to bottom. Across the rank and file, its officers and soldiers were simply not very good, not highly competent except for a narrow range of skills defined by unit function and ranks.

The really good Soviet officers wrote (their journals reached the West) that Soviet military exeercises in Europe were chracterized by massive foulups and snafus.

Yet the prevailing opinion of many of us junior officers (I was a captain then) and NCOs was that the US Army was not exactly a paragon of organization effectiveness or efficiency. For example, I was present when an American brigadier general said that the combat medical evacuation and treatment system in Europe was simply broken.

Any soldier, NCO or officer who took part in REFORGER exercises can recount the screwups that seemed to be woven throughout.

So I concluded that the reason NATO and the Soviets each took no action to start war was that the generals on both sides were fearful that the other side could not possibly be as screwed up as their own side.

Back in the States, I explained this theory to a goodly number of senior officers over time, and they all laughed, but none said no.

In wartime, not screwing up is often just as important as doing things right. Which brings me to Brian Dunn's exposition of the fundamental screwups of our terrorist enemies in Iraq:

I think the main reason for our success is that the Islamists with their foreign jihadis have screwed things up for the Baathists. That is, if the insurgents (or regime remnants or whatever you want to call them) had been able to target Americans and our allies without other complications, the vast majority of Iraqis might have decided to sit out the war as neutrals and just watch passively to see who will win. Absent a really ruthless American campaign, we would never win if we fought enemies in a sea of apathy that slowly turned against us as the violence continued.

This civil war strategy of the Islamists was always going to be a loser for the Baathists. A Sunni-Shia war might have been fine when the Sunnis controlled all the instruments of state power, but in a fight in which the Shias have the numbers and the state, this cannot work. At best, this path could inflame the oil-free Sunni heartland in revolt but this would not gain the entire country back for the Baathists. The Baathists could only win it all back if the Shias joined them against America as a common enemy, as some thought was happening in April at the start of the twin Fallujah and Sadr revolts.

For all the mistakes we have made, our enemy may have made the most critical of them all.