For most of Major League Baseball’s existence, there were only a few statistics that writers, managers, and owners cared about: batting average, home runs, and runs batted in (RBI) for players, and wins and earned run average (ERA, or the approximate number of runs allowed every nine innings) for pitchers. They judged the best hitters by how many home runs they slugged and how many runs they drove in, and they determined the best pitchers by how few runs they allowed. That was it, from the early 1900s all the way to the early 2000s. Once front offices brought in […]