Baseball Player Won-Lost Records

The job of a Major League Baseball player is to help his team win games, for the ultimate purpose of making the playoffs and winning the World Series. Since the early history of Major League Baseball, pitchers have been credited with Wins and Losses as official measures of the effectiveness of their pitching. Of course, Pitcher Wins are a fairly crude measure of how well a pitcher did his job, as wins are the product of the performance of the entire team – batters, baserunners, and fielders, in addition to pitchers.

While the implementation of Pitcher Wins as a measure of pitcher effectiveness is less than ideal, nevertheless the concept is perfectly sound. The ultimate measure of a player’s contribution – be he a pitcher, a hitter, a baserunner, or a fielder – is in how much he contributes to his team's wins.

Using play-by-play data, I have constructed a set of Player won-lost records that attempt to quantify the precise extent to which individual players contribute directly to wins and losses in Major League Baseball on the baseball field.

An overview of the website can be found here.

I also have a book: Player Won-Lost Records in Baseball: Measuring Performance in Context is published by McFarland and should be available wherever fine books are sold.

Thank you for visiting the site and please come back often!


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note: Player Won-Lost records are estimated for all seasons from 1930 to 2016, and a handful of earlier seasons.

The information used here was obtained free of charge from and is copyrighted by Retrosheet. Interested parties may contact Retrosheet at "www.retrosheet.org".
Baseball player won-lost records have been constructed by Tom Thress. Feel free to contact me by e-mail or follow me on Twitter.