Value Over Replacement Player - VORP For Pitchers

VORP For Pitchers

VORP can also be calculated for pitchers, as a measurement of the number of runs he has prevented from scoring that a replacement-level pitcher would have allowed. 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. As an aside, Run Average is used as a measure of pitcher quality rather than Earned Run Average. ERA is heavily dependent on the concept of the error, which most sabermetricians have tried to shy away from because it is a scorer's opinion; also, we are trying to determine VORP in units of runs, so a calculation that uses earned runs is not of very much use to us in this instance.

The "old" definition of pitching VORP, as alluded to above, was simply:

VORP = (((League Runs/Game + 1) - RAvg)/9)*Innings Pitched

However, further research indicated that starting pitchers and relief pitchers have different replacement thresholds, as it is easier to put up a low RAvg in relief than as a starter. Armed with that knowledge, Baseball Prospectus 2002 published the current formula for determining the replacement level for pitchers:

For starting pitchers, Repl. Level = 1.37 * League RA - 0.66

For relief pitchers, Repl. Level = 1.70 * League RA - 2.27

Therefore, the current formula for VORP is:

VORP = ((Repl. Level - RAvg)/9)*Innings Pitched

As was the case with hitters, run average should be normalized for park effects before VORP is calculated. Pitcher VORP is on the same scale as that of hitters.