Judging by the pictures, it does look like it's feather picking/plucking turning to cannibalism - but free ranging seems to cure that pretty quick - at least it did for me.
Do you free range all day - or only a few hours a day? Can you observe them for a few hours to see if you can determine if there is any feather picking/plucking going on?
While dealing with a similar issue with my flock, I ordered some Hot Pick and some Avia Guard 2000. But I started free ranging from first thing in the AM until last thing in the PM and the feather picking/plucking stopped before the Hot Pick got here. I did use Blue Kote - but it seemed to have no effect as far as stopping the behavior goes. Once I got the Avia Guard 2000 I started using it in their water right away. No idea if it helped as the issue seemed pretty much resolved before I got it.
My situation was quite a bit different than yours, but what worked for me was free ranging them all day and adding raked leaves and freshly mowed grass clippings to the chicken run and sprinkling it all with sunflower oil seeds to keep them busy while in the run - as that seemed to be the only place the feather picking/plucking occurred. And even though they are free to go as they please, they still like hanging in the run. I also cut out all snacks excepts the sunflower oil seeds - and once I got the Avia Guard 2000, I started adding that to their water.
You've got more to deal with than I did - you need to identify what's causing this problem before you can even begin to guess how to deal with it. While it does look suspiciously like feather picking/plucking and cannibalism, you need to verify that's what it is. If it is, and there's only one that doing this, you may seriously want to consider culling. Cannibalism is a very disturbing habit and is, by all accounts, difficult to stop once it's started. What ever it is, it looks nasty and I hope you can heal them all up.
Sorry I can't be of more help. I sure hope you get it all figured out. Please keep us posted.
Penny