The Elo ratings have been the most popular performance evaluation and prediction metric in board games, however some enthusiasts already took it to apply to international football competition. Here we attempt to evaluate team performances during a season or a postseason based on their results.
The teams start with initial rating of 2000 and have it change with every result. One of the differences with chess is that unlike chess, NHL hockey game is not zero-sum. Usually the teams split game points 2-0, but in case of overtime wins, the points are split 2-1. In spirit of the tradition, and given that the equal teams are expected to split a game 1-1, the overtime losing team has its rating recalculated as if it tied the game. Naturally, it leads to ratings' inflation, but since the ratings are reset at the beginning of each season, the inflation does not carry over. We only begin to calculate changes in the Elo ratings after five games in the season per team. Elo ratings are calculated once 20 games into the season are played.
