Agree it looks like rooster damage. .
I would pull the rooster. If you don't need him for something, get rid of him. If you want to keep him, pen him separate for a time while you work on the hens.
The other birds may also be pecking at the bare skin. That's a cycle in birds, the loss of feathers show bare skin, the bare skin encourages pecking....round and round. I'd get some Blu-Kote and spray the bare spots. The blue provides camoflauge so the bare skin doesn't stand out so much.
I'd boost the protein in the feed. I think it's Purina that makes a Feather Fixer feed for molting. I'm just not sure how much protein it has. If your birds are on layer, I'd change them to starter, aiming for around 20% protein. Cut scratch and treats, etc for a while unless it's a high protein treat. Provide oyster shell on the side if you go with a lower calcium feed like starter.
Some hens just have more brittle feathers, even if they're not especially favorites of the rooster. I've supplemented my layers with a little Calf-Manna and seen an overall improvement in feather quality, even in my concentrated breeding pens. Can't hurt, anyway. For your 5 hens I'd just to a handful a day.
You'll have to make a decision about the rooster. If he has redeeming qualities and you want to keep him, you might consider saddles for the hens, some folks swear by them. You can add more hens and see if he spreads the love a bit, although if a rooster has dedicated favorites IME he continues to mate them continuously, no matter how many other hens are available. Or, you may decide to cull him. That's one of those things you'll have to come up with the answer that fits your situation.
Good luck with your ladies, I hope you get them back to their good glossy selves
