About the rating system...
This site uses an algorithm, which is based on the Elo rating system.
Arpad Elo, a Hungarian-born American physics professor, created the Elo rating system to counteract the flaws he saw in the chess rating system being used at the time. By assigning a numerical number to every player based on competitive games, using this system allows players to be rated more closely to what actually happens on the court.
For over 50 years, the Elo system and slightly modified variations of it have been used to generate ratings for all kinds of sports and games – from chess, to online role-playing games, to the NFL.