In baseball, value over replacement player (or VORP) is a statistic popularized by Keith Woolner that demonstrates how much a hitter, pitcher or outfielder contributes to their team in comparison to a replacement-level player who is an average fielder at that position and a below average hitter.
However, league average comparisons such as Runs Created are not as informative when considering a player's total contribution to a team.
Baseball Prospectus author Keith Woolner uses Clay Davenport's Equivalent Runs in the calculation of VORP.
[citation needed] There are two exceptions to this, though: catchers, who shoulder a larger defensive responsibility than any other player in the lineup (and are therefore more scarce), have a replacement level at 75% of the league average.
Before calculating the VORP, the individual player stats must be normalized via park factors to eliminate the distortions that can be created by each ballpark, especially extreme parks like Coors Field in Denver (where the thin high-altitude air allows baseballs to travel farther than at sea level, although the humidor has significantly decreased the runs scored in Coors Field, to the extent that Denver is no longer considered a pure hitter's haven)[4] and Petco Park in San Diego (where the heavier sea air couples with distant fences to suppress run-scoring).
The concept is essentially the same as it was for hitters: using the player's playing time (in a pitcher's case, his innings pitched), determine how many runs a theoretical "replacement" would have given up in that playing time (at the most basic level, the replacement level is equal to 1 plus the league's average runs per game), and subtract from that number the amount actually allowed by the pitcher to arrive at VORP.