As far (sparring) goes it is just that, during the pre rut most of the bucks are trying to establish a certin order, a pecking order if you will, Most of the bigger more dominent bucks arent needing to establish anything, there fore you won't see to many of them playing around, by this time the mature bucks are awaer of what is comming and I belive they are more concerned with trying to build up the protine reserves for the upcomming rut. Now in my experience during the rut is when you will find the big guys going at it. This is what they care about. I am a firm beliver in rattling during the rut, pre rut, not so much.