How are the game-based ratings and player-based ratings combined to form the SPI rating?
The SPI ratings really consist of two distinct (though interrelated) ratings systems, which are combined to provide an overall assessment of team quality. One of these — the game-based ratings — reflects the team’s results in recent international play. The other — the player-based ratings — reflects the performance of individual players in both international competition and club play (specifically, the “big four” leagues: English Premier, Spanish Primera, Italian Serie A, German Bundesliga — plus the European Champions’ League). The extent to which we weight one rating over the other depends upon the relative amount of data we have in each category. For instance, in the case of Russia (which has very few players in the big four leagues), the overall rating is based almost entirely on its game-level results. For a team such as England, whose roster is loaded with players who compete on elite teams in the Premiership or other major European leagues, the player-based ratings are more
