I'd imagine as AFL is such a professional sport that one or two percent difference (e.g less injuries, or better preseasons for the boys, or a couple of extra talented kids pushing the older brigade) could make a huge difference in overall performance of teams. I'd imagine that probly 10 or so of the teams are almost identical skillwise and talent wise (to an extent) and these sort of factors would probably determine their position and how their seasons went. Along with the heart of the players and coaching.