Not only tree size, I also look at the depth of the rub, & possibly the size of the gouge. the wider & deeper the gouges, more than likely a larger buck produced it. Last yr. I had a good size buck rip up little saplings, I mean just trash them, bent over, all busted up. Near by, he marked up a tree about 2-3' up a tree & I'd say 10" around. Never seen him doing it though. Did get a shot at him. Maybe this will be my year.