Here's a book for all those interested in ranking football teams, race horses, tennis players or any other sports team or individual. In the past I have mentioned Rateform an Elo style ranking system that was mentioned in the Punter's Revenge. This book covers the science of ranking and rating from every conceivable angle.
Written by two American mathematics professors, the book uses American football to explain various ranking methods. The methods can easily be adapted to any other sport that lends itself to rankings.
Methodolgies include Massey's, Colley's and Keener's methods. You will need to know matrix maths but that shouldn't be a problem.
Elo's chess ranking system is given a chapter and its application to team sports. Then probabalistic models are covered with the Markov method. Other chapters cover reordering methods, point spreads, weighted rankings and rank aggregation.
There is plenty to keep you busy with ranking sports teams but as mentioned early on, each method has its merit but no method is foolproof. Arrow's Impossibility Theorem is given and states that no ranking method is perfect.