Lt. Van Steenwyk does the journalist's job for him in this perceptive post. In it, he makes this very valid observation:

We have turned a corner. We are focusing on an entirely different kind of insurgent, now. The foreign fighter-dominated jihadist terrorist cell is a very different animal from the former regime loyalist. Their tactics may be similar at times, but the channels through which they receive support --hence their set of critical vulnerabilities--are totally different. They are financed differently, they are armed differently, they are motivated differently, they are recruited differently. They pray differently, they communicate differently, and have an entirely different set motivations.

It's just possible, but only just, that the monster troop rotation happening right now ended up being timed just right. Different faces, different ideas, all ready to face a different foe. Of course, it could also be said these new people just spent the past several months training to shoot the wrong insurgents. However, as long as the commanders on the ground are allowed to do their job I have a feeling the new insurgents will go the way of the old.