While the Afghan Army is kicking the crap out of the Taliban, corrupt officers and NCOs are weakening the discipline and resolve of the troops, and those leaders who are not on the take. The biggest problem is pay, which is delivered, each month, in the form of cash payments. Some units go months without pay, or don't get the full amount. The money is being stolen by corrupt officers, who turn around and blame "bandits" or "Taliban" or the government for the missing money. Units often receive cash to buy food, and other supplies, locally. Again, cash has a tendency to disappear before it can be used for what it was intended for. Some of these corrupt officers will take bribes from the Taliban to look the other way, as the bad guys go about their business.
In units where the pay and food disappears, the troops become undisciplined, and resort to looting or extorting money and goods from civilians. Many troops simply desert. U.S. advisors who report these problems often find out that the wayward officer has a senior government official "protecting" him. Often there's a network of corrupt officers and NCOs, looking out for each other. The problem is an ancient one, and can be summed up with; "there are no bad soldiers, only bad officers." But it takes years to develop good officers and NCOs. After eight years of effort, and over $15 billion, the U.S. still has work left to do. About a third of the units in the ANA (Afghan National Army) continue to have serious leadership problems.
The Afghans have some of the same problems as the Iraqis, namely tribalism and a weak sense of nationalism. With four major ethnic groups (Pushtun, Tajik, Uzbek and Hazara), and dozens of powerful tribal organizations, its been difficult to get Afghan recruits who are willing to serve in the national interest. Ethnic and tribal loyalties are always stronger. But European colonizers proved in the 19th century that, with good training and good NCOs and officers, you can produce combat and police units from tribal warriors that can match Western ones in effectiveness. The key problem is getting effective NCOs. Its the sergeants that supervise the troops, and keep order in the barracks. Professional NCOs have been the secret to success in Western armies.
However, the NCOs must be slowly developed, by selecting recruits who have leadership and management skills, and training them, on the job, over several years. It takes 3-5 years to get a suitable recruit to the point where he can handle the job of the lowest level sergeant (in charge of 10-12 troops or policemen.) Another 3-5 years gets you an NCO that can handle a platoon (3-4 squads, which is usually led by a lieutenant, who depends on the platoon sergeant a lot.) Another five years gets you a company 1st sergeant. This NCO assists the officer commanding the company, and supervises the other twenty or so NCOs in the company.
The Afghan police mostly operate in rural areas, where they function as a paramilitary force. They sometimes have to deal with large groups of several dozen armed tribesmen. If negotiation fails, the police are frequently forced to fight. The American advisory teams are there to show, by example, how experienced NCOs operate in combat, and how trained troops are more effective when supervised by a good NCO. While most Afghans prefer to negotiate, they appreciate the training that makes them more effective in a fight.
Western nations have, in major wars, had to develop NCOs a lot more quickly. This was the case in the two World Wars, and as recently as the Vietnam war. When you are conscripting a lot of troops and creating many new units, the number of experienced soldiers is spread pretty thin. So you get shake and bake NCOs. These are young men (and some women) who have the leadership and management skills who are first selected (using tests and their performance in basic training), and then given some training on what NCOs do and how they do it. During World War II, there were many platoon and 1st sergeants in their 20s who did quite well, after only 2-3 years in service. The advantage you had in this situation was lots of live examples of effective NCOs for the new guys to emulate.
In Afghanistan, you had a lot of men who have been fighting for over two decades. Lots of good NCO material. But the concept of the Western NCO (a professional supervisor who is respected and well paid) is largely unknown in Afghanistan. The old Afghan army was based largely on the Soviet model, which treated most NCOs as senior privates and left most of the supervisory duties to officers. Most of the Afghan men with combat experience, however, were not in the army, but in tribal war parties (usually squad or platoon size). Here, many of them gained good NCO type experience at the squad and platoon sergeant level. These men have been found and given some training for squad and platoon sergeant positions. Those that are at the platoon sergeant level, and are also literate, are being used as 1st sergeants (who have to handle some paperwork).
Another advantage the Afghans have over the Iraqis is a warrior mentality. Its easier to make the Afghans understand that for an army to work, troops must learn how to use their weapons (and take good care of them), and stand and fight. While Iraq has produced some good soldiers, most Iraqis want nothing to do with fighting. However, with good training and NCOs, just about anyone can be turned into an effective soldier. But you need competent NCOs to create more competent NCOs. The police have a lot of inexperienced leadership. These men are more prone to corruption, as well as incompetence. The experienced American advisor teams are going to find out how much they can change that in a year, especially for the police, but also for the army.