Multiple columns on this website have focused on resources focusing on the mathematics underlying the playing and understanding of various sports. And, the columns will continue...
A recent addition is Wayne Winston's book Mathletics: How Gamblers, Managers, and Sports Enthusiasts USe Mathematics in Baseball, Basketball, and Football. Winston provides interesting discussions on multiple aspects of using mathematics within the major sports.
In the forward, the author states his goal is "to demonstrate how simple arithmetic, probability theory, and statistics can be combined with a large dose of common sense to better evaluate players and game strategy....(plus) show how math can be used to rank sports teams and evaluate sports bets." He does that well, while providing both interesting stories and useful insights.
His specific examples involving actual players are supported by reader access to downloadable Excel files. Specific to baseball, the reader can explore topics such as hitter and pitcher evaluations, park factors, streakiness, and platoon effects. Specific to football, the reader can expore topics such as quarterback ratings, passing versus running, conversion options after touchdowns, the flawed overtime system, and the draft pick process. Specific to basketball, the reader can explore topics such as lineup analyses, prejudices of officials, player evaluations, and end-game strategies. Throughout the book, Winston's applies his background in operations research and decision analysis.
Again, if you have mathematics-related-to-sports resources to add to this list, please let me know.