I too would guess he missed. I have killed a bunch of deer with a bow and can't recall one time that I didn't hear the hit. That telltale thwack always tells me I hit it. I have on occasion had very little blood and no visible hair that I found but an arrow hitting a deer will always leave something at the site. In all likelihood he could have missed high and the arrow deflected away from a branch. I never had a hit deer blow at me.