Here is my main criticism of Bacevich's piece:

Classifying the two sides of the debate as Crusaders vs. Conservatives seems remarkably unfair.

In Bacevich's description the "Crusaders" become COIN ideologues instead of what they should be viewed as: COIN innovators. I don't mean innovators in the sense that they have re-invented the wheel here (how groundbreaking the operations and tactics behind the "Surge" strategy are is the subject of another conversation).

Petraeus, Nagl, McMaster, and those like them haven't fought for COIN because its always the right answer- they have argued that a COIN strategy is best for THIS war. None of them strike me as so committed as seeing COIN as the panacea to future conflicts. Moreover, these innovators are as aware as anyone of just how hard and resource intensive COIN can be. To successfully implement a COIN strategy in every future conflict would be expensive, counterproductive, and maybe even dangerous.

Nagl, for example, has recently been pushing to increase US training capacity (more of a FID capability). The COIN innovators dont qualify as COIN ideologues: they are asymmetrically focused, perhaps, but not blinded by a crusade for COIN. To suggest otherwise, as I read Bacevich doing, seems to miss the point: strategic flexibility is the only cure to a rigid adherence to prior assumptions- this will be even more true in the future.