A rating system assigns every team a number that rises with good results and falls with bad ones. It turns messy results into a single, comparable measure of strength.

Elo-style systems are a great starting point: they are simple, transparent, and easy to update after each match.

The key choices are the starting ratings, how much a result moves a rating, and how to handle home advantage and margin of victory.

Once built, a rating system lets you estimate win probabilities, spot overrated and underrated teams, and test your ideas honestly over time. Set limits and never bet what you cannot afford to lose.

See the final section of the full article for additional practical guidance on this topic.