Value over replacement player

In baseball, value over replacement player (or VORP) is a statistic popularized by Keith Woolner that demonstrates how much a hitter contributes offensively or how much a pitcher contributes to his team in comparison to a fictitious "replacement player," who is an average fielder at his position and a below average hitter. A replacement player performs at "replacement level," which is the level of performance an average team can expect when trying to replace a player at minimal cost, also known as "freely available talent."

VORP's usefulness is in the fact that it measures contribution at the margin (as in marginal utility). Other statistics compare players to the league average, which is good for cross-era analysis (example: 90 runs created in 1915 are much better than 90 RC in 1996, because runs were more scarce in 1915). However, league-average comparisons break down when considering a player's total, composite contribution to a team. Baseball is a zero-sum game; in other words, one team can only win if another loses. A team wins by scoring more runs than its opponent.