Poor baby! A couple of my boys looked this bad before I figured out what was going on. They were young still and all of them were boys so I knew it wasn't damage from mating. It's hard to tell because of the shine, are there any actual breaks in the skin? It doesn't look like there are any big ones if there are. So what may be happening is that your flock is lacking protein so they're eating feathers, and the pin feathers are especially attractive.
With my boys, I did a couple of things all at once, so it's hard to tell what exactly fixed the problem. Covering the bare spot/pin feathers with a saddle, blukote so it was harder to see when uncovered, and added protein to the diet (canned cat food, meal worms or scrambled eggs). It took a month at least to get all the feathers grown in, but once they did I kept up with the protein and never had another problem before slaughter.
With the girls, I cover them with a saddle the instant I see a patch and keep them covered until I can't see pin feathers. I also give them extra protein the next few days after finding the patch. When I got geese I switched everyone over to flock raiser and the problem got quite a bit better. The girls were still a little ragged looking because of the rooster, but no patches. A couple weeks ago I switched the chickens over to layena (lower protein), and a couple of patches showed up, so I've made sure to add protein and there haven't been any new patches.