Yeah, you can't look at his feathers while they are wet, as that area of his belly is where his down is thickest and it will not look normal until it is completely dry. And typically they will preen themselves to get their feathers feeling and looking right to them after a bath or shower, so give him some time.
To me, based on your Indian Ringneck's age (he is not an Alexandrine by the way, he's an Indian Ringneck) he is simply going through his first big molt, which is perfectly normal. When those body feathers that you showed in your photo come out like that, in multiples, that's a very good indication that it's due to molting, not due to plucking.
So my best suggestion is to not get upset from this point through the next month, as it 'tis the season for our parrots to look a little scruffy, lol. Indian Ringnecks are beautiful birds, and he is a beautiful looking IRN, but when in-molt, especially right in the middle of it, they can get to looking pretty ugly. Give it time, and do not be surprised if it gets worse before it gets better.
Also, keep an eye on him and watch to see if he's actually forcefully plucking his feather out...Now I'm not talking about him preening himself and possibly seeing some fluff come out, that's normal. However, if you actually see him forcefully yanking any of his feathers out, specifically any of his long tail feather, flight feathers, etc., OR if you see him lose a very large amount of feathers in one particular spot, like his chest, where you start to see an actual bald spot, then that's another story. But that doesn't at all appear to be what your IRN is doing at all, he's simply going through his first big molt. All birds molt, some more than others, but it's perfectly normal and not an indication of anything that is wrong. Also, I'm assuming that he is not showing any other signs or symptoms of illness, such as lethargy/sleeping a lot, fluffing-up a lot, being on the bottom of the cage a lot, vomiting, lack of appetite or thirst, etc.
