Editing Value over replacement player (section)

==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 (RA9) is used as a measure of pitcher quality rather than [[Earned Run Average]] (ERA).{{Citation needed|date=September 2009}} ERA is heavily dependent on the concept of the [[error (baseball)|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:{{Citation needed|date=September 2009}}

:<math>VORP = IP \cdot {{({{League R \over League G}} + 1) - RA9 \over 9}}</math>

where

*''R'' = [[Run (baseball)|Runs]]
*''IP'' = [[Innings pitched]]
*''G'' = Games played
*''RA9'' = [[Run average]], sometimes written as RA

RA9 is calculated for the pitcher in question as

:<math>RA9 = 9 \cdot {{R \over IP}}</math>

''[[Baseball Prospectus]] 2002'' revised the formula to reflect different replacement thresholds for starting pitchers and relief pitchers, as it is easier to put up a low RA9 in relief than as a starter.

:'''For starting pitchers,''' <math>Repl. Level = (1.37 \cdot League RA9) - 0.66</math>
:'''For relief pitcher,''' <math>Repl. Level = (1.70 \cdot League RA9) - 2.27</math>

Therefore, the current formula for VORP is:<ref>{{cite web|last1=Barnes|first1=Nate|title=Ultimate Guide to Value Over Replacement Player - VoRP|url=http://www.sportingcharts.com/articles/mlb/ultimate-guide-to-value-over-replacement-player-vorp.aspx|website=Sporting Charts|access-date=29 August 2016}}</ref>

:<math>VORP = IP \cdot {{Repl. Level - RA9 \over 9}}</math>

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.