ABSTRACT
The goal of a baseball team is, just like in any other sport, winning games. Similarly, the goal of the baseball analyst is being able to measure what happens on the field in term of wins. Victories are obtained by outscoring opponents, thus the percentage of wins obtained by a team over the course of a season is strongly correlated with the number of runs it scores and allows. This chapter explores the relationship between runs and wins. The Teams table from the Sean Lahman package contains seasonal stats for major league teams going back to the first professional season in 1871. The run differential is defined as the difference between the runs scored and the runs allowed by a team. The winning proportion is the fraction of games won by a team. Residuals can be interpreted as the error of the linear model in predicting the actual winning percentage.
