More bucks die from wounds occurred from fighting during the rut than we may likely expect according to nationally known wildlife biologist. I found two decomposing mature bucks dead this winter on the farm with no apparent visible injuries. One was a 150's class deer. The estimated 5 1/2 yr, over 200# cull, that I harvested this past season had a huge gaping puncture wound in his neck. I would suspect that the placement of that particular wound was not far off the mark from having been lethal.
Several years back, one of the prominent bowhunters in North America and I encountered a fight scene, here on the farm, that resembled a homicide crime scene. The blood spray and droplets and pools completely covered an approximate area from 6 yards wide to 15 yards long. My hunter, who has a deer hunting school, traditional archery school and is whitetail hunting author was calling guys all over the country, including Roger Rothhaar, from the crime scene. I would suspect that one of those deer did not survive.
We may just not know what was the cause of death.