if you look at the oblong shape of it and even the bark below and obove the main area of it you can see that whatever has happened has happened a hell of alot more than once like a tire rub and the heighth is right for a deer rub, I am going to say that it is probably a sign post rub and is rubbed all the time that's why it does'nt have noticable brow tine gouges. I think it has been rubbed alot and probably by a buck that has fairly smooth bases.