Apologies if this is already answered, but I looked in the forums and in the docs and couldn't find any info.
My question is what does the rating of each player signify (if anything), and how is it calculated?
We use TrueSkill, which keeps track of mu (estimate of skill) and sigma (uncertainty about the estimate). mu and sigma are updated after each match you play. Your score, which determines your rank, is mu - 3*sigma (a conservative estimate of your skill).