Hi The Hen Whisperer,
Yes, I would say that is from over mating. I found two of my breeding hen last month in the same condition. I bathed them, cleaned their wounds, blow dried them (which they love) and placed them in an area away from the roosters to heal.
I hate to report that sadly one of the hens did not make it. I barely even noticed her wound. It was under her wing. It wasn't very large in size, but it must have been infected for sometime, because it was super deep and oozing yellowish-green pus. The other hen was ripped up way worse on both sides right down to the flesh, but she recovered nicely and has been doing well for over a month now. I have since noticed that the roosters in that breeding pen are super aggressive with the hens. I haven't yet decided what to do with that breeding stock because the two roosters I have are just gorgeous.. (maybe I will raise up their offspring and replace them, hoping for less aggression and adding more hens to prevent ripping).
Keep and eye out for your hens even after they heal because the surviving hen immediately got ripped up again (not very badly, right it happened right after just one rooster mated her) I now keep her out of the breeding pen and placed her in with our backyard flock where there's enough hens running around that the roosters don't bother her. She's happy!!
I hope your hens recover nicely.