Gross Productivity Average, or GPA, is a new baseball statistic that measures performance. Accounting for the effect that each plate appearance or baserunning play has on scoring opportunities, it is reported on a scale similar to that for batting average, making it easy for the average fan to understand. Beginning with a detailed explanation of the statistic and its derivation, the book identifies, in Part II, historical patterns in league-average GPA (even the steroids effect is quantified). Practical applications are then explored, as GPA is used in Part III to settle long-running arguments about strategy and in Part IV to reassess players and awards voting from 1952 to 2012.