Applying a slide rule to baseball

The book and subsequent film Moneyball tell the story of Billy Beane, the general manager of Major League Baseball's Oakland Athletics. To compete against richer teams such as the New York Yankees and Boston Red Sox, Beane began to look closer at the statistics of undervalued players who could help his team score runs without inflating the payroll. Beane's approach was grounded in a form of baseball data analysis that has come to be known as sabermetrics, defined by one of its foremost practitioners, Bill James, as "the search for objective knowledge about baseball."

James brought sabermetrics to popular attention in the 1980s, but one of the seminal works on objective analysis of baseball data was written by a Johns Hopkins professor of chemical engineering named Earnshaw Cook. The MIT Press published Cook's Percentage Baseball in 1964, and in the foreword he wrote, "This book has been written for those aficionados of percentage baseball who have managed to retain vestigial recollections of freshman mathematics. In a small concession to sanity, many derivations and calculations have been relegated to separate tables as less to interfere with continuity of discussion. The argument is not difficult but it is complicated because baseball is an exceedingly intricate game." Cook's publisher noted, "Among other theories that Cook attacks with irrefutable mathematical findings are the benefits of the sacrifice bunt, the use of relief pitchers, the traditional batting order, the hit-and-run play, and the standardization of baseball itself."

In Percentage Baseball, Cook, who was born in 1900 and died in 1987, notes that his father played shortstop for Gettysburg College, one of his uncles played for Lehigh University, and a distant cousin, George Earnshaw, won a league-high 24 games as a pitcher with the Philadelphia Athletics in 1929. Sportswriter Frank Deford interviewed Cook for an article in Sports Illustrated when Percentage Baseball was published, and recalls, "I remember him as quite the gentleman, extraordinarily helpful to someone like me who was so ignorant of math. He had a nice little sense of humor. He loved baseball and was amused that it was still played more traditionally than realistically. As such, he was well ahead of Bill James and all the latter-day statistical savants. Earnshaw wasn't smug about his statistics. He just was astonished that nobody had figured it out before him."

The sabermatrician James does not concur with MIT Press' assessment of Cook's work as "irrefutable." In his 1981 self-published Baseball Abstract, James wrote, "Cook knew everything about statistics and nothing at all about baseball—and for that reason, all of his answers are wrong, all of his methods useless." Wrong or not, Cook—or at least a copy of Percentage Baseball and the slide rule that he used while working on it—is part of the permanent collection of the National Baseball Hall of Fame and Museum in Cooperstown, New York.