My biggest problem with these predictions is retroactive analysis of the prediction itself. If I have Brazil at a 99% chance to win the WC and they win, is my m

My biggest problem with these predictions is retroactive analysis of the prediction itself. If I have Brazil at a 99% chance to win the WC and they win, is my model the best? I guess the idea is that over time, you measure prediction performance, but models are constantly changing and there's enough time in between WC tournaments that it'll take at least a century to have a good sample size of predictions. If you take something more immediate like predicting tomorrow's stock prices or even the market (up/down), I wonder how their prediction models would fare.