Given the face angle, shoulder/neck junction, short looking legs...I'd put that deer at least seven years old. Face angle is a dead give away.....
I see what you're talking about with the face angle now. His nose looks short. He'll probably never show his face in the day time but I've got a 12 year old son that would fall flat over if he could put a bullet in him.
You think a buck that's past his prime like this one could would change his territory after being beat down by a younger buck? I know antlers can change from year to year but I don't have a picture of a mature buck from last year that I can assign to this one, and this one is around every day.