The Elo system was originally designed for chess rankings, however it is very similar to the current system used by XBox live to match people to games that are similar in skill. The skill difference assumes that the only relevant piece of information is the win or loss record. The strength of the win would be important if you look at a single game and say "Which team is better", but in the long run a win/loss record should suffice if you have the relative strengths of the teams. Obviously if the strategy used by a team doesn't fit well with others, then it's skill rating being high is irrelevant. However, the nature of the statistics makes it unlikely that a team that doesn't do well in points, or doesn't do well with others, will come out ahead with a high score. The system I used is to treat each match won or lost as a group of 1 on 1 matches, and is the system used by many other implementations of Elo used for team matches. The XBox Live TrueSkill is slightly different, but it's implementation is a project which takes more free time than I have
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Example: If a weak team gets a "free ride" with higher rated teams, it's skill will go up. However this is negligible because with the sheer amount of teams that play, it balances out in the long run with probability.
-Niles
Team 294