Game score is a metric devised by Bill James as a rough overall gauge of a starting pitcher's performance in a baseball game. It is designed such that scores tend to range from 0–100, with an average performance being around 50 points.

George William James is an American baseball writer, historian, and statistician whose work has been widely influential. Since 1977, James has written more than two dozen books about baseball history and statistics. His approach, which he named sabermetrics after the Society for American Baseball Research (SABR), scientifically analyzes and studies baseball, often through the use of statistical data, in an attempt to determine why teams win and lose.