Player Won-Lost Records in Baseball ─ Measuring Performance in Context

Baseball analysts often criticize pitcher win-loss records as a poor measure of pitcher performance, as wins are the product of team performance. Fans criticize WAR (Wins Above Replacement) because it takes in theoretical rather than actual wins. Player won-lost records bridge the gap between these two schools of thought, giving credit to all players for what they do—without credit or blame for teammates’ performance—and measuring contributions to actual team wins and losses. The result is a statistic of player value that quantifies all aspects of individual performance, allowing for robust comparisons between players across different positions and different seasons. Using play-by-play data, this book examines players’ won-lost records in Major League Baseball from 1930 through 2015.

Economist Tom Thress, has been a SABR member since 2003 and has had research published in By the Numbers and the Baseball Research Journal. He lives in Chicago, Illinois.