Recent advances in sabermetrics have made it possible to assess the exact contribution of each player to the success of failure of his team. Using the simple metric Wins Above Average-the number of wins that the 2016 Red Sox, for example, added to their total because they had Mookie Betters in right field instead of an average player (5)-David Kaiser leads us on a fascinating tour through the history of major league baseball from 1901 through 2016, analyzing all the greatest players and teams of the past and showing exactly why they enjoyed the success that they did. Along the way, he identifies the 15 or 20 greatest players of every generation, using simple metrics that allow him to compare the impact of players from Ty Cobb through Ted Williams to Willie Mays, Rickey Henderson and Barry Bonds, and pitchers from Christy Mathewson to Roger Clemens. The book also says a great deal about short- and long-term strategies for organizational success. Along the way, Kaiser takes on a good many tenets of diamond faith.. The importance of pitching, he argues, has been vastly exaggerated since the beginning of baseball time, and great pitching has almost never been the key to a dynasty. Many Hall of Fame pitchers and some hitters as well, he finds, have reached Cooperstown almost entirely on the backs of their teammates. Accurate metrics also reveal that a few over-qualified players are still awaiting selection to Cooperstown. Last but hardly least, Kaiser shows that baseball is threatened by an unprecedented shortage of great players, and challenges MLB to do something about it.