Those simulations are used to calculate the public leaderboards during the competition. They aren't used for final rankings as the simulation results need to be validated. However, they provide a nice way for people to gauge their standing.
To perform the final ranking/validation, we'll play n of the top games on each team against each other and then sort by wins and losses. We're not quite sure of how large n will be, but I think it will be 150-250. It would be nice to calculate the public leaderboards this way, but as a O(n*m) calculation, it really doesn't scale in practice (we have to strike a balance between accuracy and responsiveness of the ranking system). The public leaderboards are calculated with a Bayesian algorithm.
If you have any other questions, feel free to ask! :)