How could they possibly come up with those numbers? lol. As someone who recently took classes in Probability and Statistics, I'm also curious as to how they got their numbers. If these numbers were legit, my guess would be that they did some statistics on how past decisions have been made. Or they could have just have an arbitrary numbering system. The guaranteed wins are given a rating of above 80%, etc... Just so that they could say, "Well, we did say that [X] winning had y% chance of winning" in the event of an upset. This way, they would never have had made any wrong predictions.
I like your imperturbable perspicacity.