I would imagine that there is a good chance that it is a buck that is on the regress. Looks like pretty good body size like a mature buck which leads me to this conclusion. He may just be a freak of nature or just poor genetics, who knows?
I'm not sure he is regressing most of those bucks that I have seen are thicker, he looks like poor genetics to me. Just my half arsed opinion though. A good herd management buck all the same. Eat him before he spreads those genes too much! Great pictures.