I'm guessing that they didn't get a month of quarantine where they could see and hear each other, but not touch.
It sounds as if the damage is extensive and might require the assistance of a vet. If a vet is not an option and if his symptoms persist for the next few days after you've cleaned and dressed his wounds, you might consider humanely putting the poor fella out of his misery.
On the flip side, he may have been trounced so thoroughly that he wouldn't dare crow if his life depended upon it, for fear of offending the victor of this recent battle.
Put the beat up guy into an dog cage or other separate housing arrangement where he is still seen and heard by the rest of the flock in anticipation of a successful recovery and a less traumatic (re)introduction to the flock. Administer antibiotics (often available at your feed store), and one BABY aspirin daily for pain.
Keep your eye on his progress to determine your next course of action.