Help me win an argument

For the past few months my co-workers, the same people who claim that a 4-0-1 club fighter (this one: http://www.boxrec.com/list_bou.....;cat=boxer) is the best fighter in the world, pound-for-pound, have been claiming that Wladmir Klitschko's last three fights against Calvin Brock, Ray Austin and Lamon Brewster were all fixed because there was no way Klitschhko could legitimately beat any of them. I'm sure they'll say the same thing about tonight's Klitschko fight when I talk to them on Monday.
They especially referred to the Brewster fight as an obvious "acting job" by Brewster.
Obviously, we know that Klitschko could and did legitimately beat all three of those guys and there was nothing dubious about any of those fights, but how can we prove it to someone who says otherwise?
I asked one of my friends for what proof he had the Brewster was acting and he said "My own two eyes."
Obviously, my mistake is arguing with idiots, but how can I win the argument?