Sabermetrics, the systematic analysis of baseball statistics, has evolved over time to resemble something of a science, attracting fans from diverse professional and educational backgrounds, all fascinated by both the analysis itself and the objective insights it provides into the game. Although fans and analysts have devoted exhaustive efforts to developing statistics that measure offensive performance, defensive metrics have historically been deemed too difficult to measure accurately and objectively. In Wizardry: Baseball's All-Time Greatest Fielders Revealed, Michael Humphreys introduces a system that conclusively quantifies fielding statistics and compares player performance from as early as 1893 by estimating how many runs each fielder "saved" or "allowed." While a number of methods for analyzing defense have recently gained exposure, they rely on expensive proprietary data held by professional sports statistics companies and only capture information drawn from the contemporary era. Humphreys' method, Defensive Runs Analysis (DRA), makes unique use of free, open source data available to the average fan and incorporates equalizing historical factors to place players from different eras on equal footing. Wizardry is the first book to systematically rank and profile the greatest fielders at each position from throughout major league history. To frame and validate his results, the author tests DRA data against other well-known statistical measures and also presents an analysis of other defensive statistical metrics. Casual fans with little mathematical background will appreciate Wizardry's accessible style while professional statisticians will value the opportunity to validate Humphreys' methodology and results. Given the topic and the author's presentation of the material, the book will draw in both the serious, baseball statistics audience and the average fan.