To get back to your original point, parts of (1) and (2) are due to improved COIN doctrine and implementation. However, they are also due to AQI missteps, coupled with a sudden Sunni ability to count (that is, a realization post-Samarra by Sunni tribal and militia leaders that they needed protection against an angry, well armed, and larger Shiite community/militias).

(That being said, success is, in part, capitalizing on opponent errors.)
I like it when the enemy screws up - it makes for less work, but don't sell short the ability to understand a mistep/screw up and capitalize on it. Too often an enemy gives us an opportunity and we ignore it, miss it, or screw it up.

I like your second part Rex - there is some art in being a good counter-puncher.

Best, Rob