I think it can change, but you are right, it takes time to sully an award that had so much credence in the past.
The AFL are really going for it though with the Brownlow.
I think it will be pretty hard to sully it. As much as people carry on there haven't been many shockers this century. I don't consider a non favourite winning as a shocker. It's a subjective award. So long as the winner was in the mix I see them as deserving. By that definition Woewodin and Priddis are probably the only shockers this century. Maybe Judd in 2010 too but I think him and Swan's wins kind of cancel each other out.
It would have been way worse in the past. We just don't remember. I mean people are carrying on this year about players getting 3 votes in losses. Bob Skilton is remembered as an all time great for winning brownlows in a team that finished 4th last, 2nd last and 4th last. He would struggle to win a single medal with the way umpires vote today.