I always wonder if those people have tried to fit their approach to past results. Could they simulate past World Cup results to be sure their method is sane by using player/team's archived statistics?
3.4 Combining methods
[...] are now compared with regard to their predictive performance.
For this purpose, we apply the following general procedure:
1. Form a training data set containing three out of four World Cups.
2. Fit each of the methods to the training data.
3. Predict the left-out World Cup using each of the prediction methods.
4. Iterate steps 1-3 such that each World Cup is once the left-out one.
5. Compare predicted and real outcomes for all prediction methods.I'm sure an accurate model has to be updated as culture and technology changes and impacts the game itself.