I'm mostly an Asia guy, so we're coming from all over. That's not necessarily a bad thing, if we're looking for large-scale trends.

Kenneth Pollack's book proves that Iraq has a history of very poor tactical performance.
Iraq is not alone in this. I suspect that in many cases the cause of consistent poor performance is the selection of military leaders on the basis of personal loyalty to the national leadership, rather than on the basis of competence. When leaders view their own military force as the primary threat to their position, as is often (and often justifiably) the case, this is a natural evolution. In many cases it works adequately, as long as the military in question is only expected to impose internal security against fragmented opposition. Once that military comes up against a capable foreign antagonist or a competent insurgency, it collapses like a watermelon hit by an SUV.

It's easy for the Western adviser to look at this type of military and see exactly what needs to be done to make it effective. The national leadership, on the other hand, is likely to be less concerned with effectiveness than with preserving personal loyalty and personal control. The national leadership may see this as a necessity for its own survival, and may actively seek to undermine reforms that could promote effectiveness but reduce personal loyalty. Just an example of how an adviser's perception of need can vary from the host country counterpart's perception.

Americans in particular often base assessments of efficiency, effectiveness, capability on different criteria than those applied byt local counterparts. All of these are simply measures of the degree to which a system accomplishes its purpose. If we assume that the purpose is "national development" or "national security", a system may seem inefficient. If we understand that the actual purpose of the system is to preserve the wealth and position of the governing elite, everything changes. The point, simply, is that we cannot assume a common purpose... and when divergence of purpose becomes extreme, it may be better just to walk away.

What can we do about it now? This is not about armies, it's about the political evolution of the state - statebuilding. One has to improve the nature of the state before we can improve the army.
I've done this rant before, but I think it's relevant.

We can't build states. Nobody can, because states aren't built, states grow. The difference may be semantic, but it's significant: when we speak of "state-building" we slant ourselves toward an engineering proceess, one that only requires the right plans, tools, and execution. That's not realistic, and I think if we draw our metaphors from agriculture rather than engineering, and think of cultivating rather than building, we emerge with a more accurate perspective on what we're trying to do.

We also have to accept that the process by which states grow is often very messy. The US fought one of history's bloodiest civil wars and carried out one of history's great genocides on its way to nationhood. The ever so civilized western Europeans... well, we all know what they went through on the way to where they are. Why should we expect today's emrging nations to sort out their external and internal problems in an orderly and peaceful fashion when we couldn't do it ourselves? We may at times be able to mitigate the mess and prevent it from overflowing... but we're deceiving ourselves if we think we can make state-growing anything but an uncertain and sloppy process.

Rambing off topic, time to stop!