why male cats getting abscesses by tail base?

Its a recurring thing in my part of town. I help my neighbors with TNR and we have noticed recently a few males all showing up with abscesses by their tail base. I read online that its common for young males to get bite wounds there because of mature males defending territory and they try to bite the testicles off the younger males.

That doesnt sound right to me though. Also that would mean there is an aggresive male in the area but we are all out during late hours of the night and never see any mature aggressive males in the area.

What do you guys think? Is there an aggresive male who is working behind the scenes attacking these younger cats? Should we be concerned? If there is an aggresive male we would like to get him nuetered but how can we if we dont even know where he goes?

Thanks.

Oh that's weird but I suppose it's possible. I've TNRd about 35 cats, and only one had a wound (arm area).
The only other explanation I can think of is: what type of fences, objects are around the area? Maybe they are pooping/peeing in/on a place that has nails. Also going through a wire fence might cause a wound. It's far fetched--but so is a male cat biting that area. The neck is more accessible.
ANY possibility a inhumane human is doing it?