A friend of mine got drunk last weekend. He has been in AA for a bit, was doing well, took the foot off the gas, and, with no warning, drank. He was not greatly upset or anything. He just drank.
If you take an action (taking one drink) that inevitably triggers a chain reaction with devastating consequences, the problem is the lack of feedback mechanism to stop you. That is the powerlessness. Unmanageability could be said to extend naturally from this: if one is powerless over whether or not one drinks, and then how much, and therefore the consequences, one is not in any sense managing one's life—the course of one's life is essentially dictated in large part by whether the switch flicks in one's head.
One may or may not be messed up. In fact most people in AA are, at the beginning. But the danger of presenting the symptoms of being messed up (restless, irritable, discontent; or the page 52 'bedevilments'; or any number of other symptoms) as themselves being the trigger for drinking again means that, if one is free of such symptoms, one might think oneself safe. Probably one is, but not necessarily. One unmade amend, one dirty secret, one unpaid bill could be the invisible stone in the shoe.
Most people in AA seem to have both psychological problems and moral problems. The inventory in Step Four, after all, is called a 'moral inventory', not a 'psychological inventory'. The questions in the Step Four aim more squarely at moral deficits (selfishness and self-centredness) than at discovering the aetiology of cognitive quirks, say.
The seven 'death threats' (those problems that, if left unaddressed, according to the book 'Alcoholics Anonymous', will result in drinking) are more moral than psychological (though they have psychological elements): resentment, secrecy, harm to others, unmade amends, unpaid creditors, complacency, failure to place oneself in service to others.
It is likely that psychological problems will also have to be dealt with; the AA programme itself, the folk wisdom of AA, the examples of psychological wellness in our peers and elders, etc. certainly work many of the psychological quirks out over the years with no additional work necessary. Sometimes a bit of external help seems to help; sometimes not.
But it is the moral aspects that need to be dealt with (cf. the 'death threats' above) for power to be accessed to avoid the first drink. When the problem is seen chiefly as a psychological one, psychological measures may seem most appropriate, and the mental garbage is quite likely to take all of the attention. This is quite dangerous: trying to solve the psychological problems without the moral problems being addressed is largely futile, but it is also potentially deadly.
Moral soundness (in today's actions, at least) is an achievable target for any newcomer, regardless of the messed-up 'head'. Sorting the 'head' out will surely take a long time. It is in this understanding that hope lies: if the 'head' needs to be sorted out to stay sober, then good luck! If sobriety rests on the right actions today, morally, then there's hope for all of us, whatever else is going on, inside and outside our heads.