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VORP: Measuring the Value of a Baseball Player's performance

VORP (Value Over Replacement Level) is a sabermetric analysis developed by Keith Woolner that seeks to measure the contribution, in runs, of a player beyond what a backup (or replacement-level) player would produce for an average team given the same amount of playing time. VORP is adjusted for park and league, and position (for non-pitchers).

A full description of replacement level, and how it is used in VORP can be found here.

Full VORP reports for 2002 can be found on the Baseball Prospectus web site:

• VORP for position players (a single ranked list with both leagues)
• VORP for pitchers (a single ranked list with both leagues)
• VORP by position (each position and league ranked separately)
• VORP for position players by team (each team's players listed together)
• VORP for pitchers by team (each teams' players listed together)

New for 2002:

Based on research I conducted and published in Baseball Prospectus 2002, replacement level is set at 80% of the positional average rate of offense for most positions (85% is used for catchers, 75% is used for 1B/DH). Replacement level for pitchers is figured separately for starting and relieving, as detailed in BP2002:

Starting pitcher replacement level = 1.37 * League RA - 0.66

Relief pitcher replacement level = 1.70 * League RA - 2.27

Column heading for the VORP position player reports:

• NAME - Player's name
• TEA - Team
• L - League
• PA - plate appearances
• PA% - the percentage of the team's total plate appearances that this player had
• AVG - batting average
• OBP - On Base Percentage
• SLG - Slugging Average
• SB - Stolen Bases
• CS - Caught Stealing
• MLVR -- (M)arginal (L)ineup (V)alue (R)ate of production Basically, the number of runs per game the batter contributed to a league average team beyond what a league average hitter would produce. This is a rate stat similar to OPS. The comparable season total is MLV.  The "r" is usually written in lower case, as in MLVr.
• PMLVr -- Positional MLV rate. Runs/game contributed by a batter beyond what an average player at the same position would hit in a team of otherwise league-average hitters. Like MLVr, it is a rate stat. The comparable season total is PMLV.
• RPMLVr -- Replacement level MLV rate. Runs/game contributed by a batter beyond what a replacement level player at the same position would hit in a team of otherwise league-average hitters. The comparable season total is RPMLV. It differs from VORPr and VORP only in that it is solely based on batting performance whereas VORP includes basestealing.
• VORPr -- VORP rate. Runs/game contributed beyond what a replacement level player would produce. Also a rate stat.
• VORP -- Value Over Replacement Player. The number of runs contributed beyond what a replacement-level player would contribute if given the same percentage of team plate appearances.

Column heading for the VORP pitching reports:

• PITCHER - Pitcher's name code (see BATTER above)
• TEA - Team
• L - League
• G - Games appeared in
• GS - Games Started
• W - Wins
• L - Losses
• SV - Saves
• HD - Holds
• BS - Blows Saves
• IP - Innings Pitched
• H_9 - Hits allowed per 9 innings pitched
• W_9 - Walks allowed per 9 innings pitched
• K_9 - Strikeouts per 9 innings pitched
• ERA - Earned Run Average
• RA - Run Average (Same as ERA, but figured with total runs allowed, including unearned runs)
• PkRA -- A pitcher's park-adjusted RA, expressed on a scale like ERA or RA.
• RA+ -- Park and league normalized Run Average. Similar to ERA+ found in Total Baseball, but based on RA rather than ERA.
• RP - Runs Prevented.  The extra number of runs an average pitcher would have allowed in the same number of innings pitched (adjusted for park and league).  RP greater than zero indicates that the pitcher allowed fewer runs than an average pitcher (i.e. he's better than average).  Negative RP indicates the pitcher allowed more runs than an average pitcher (i.e. he's worse then average)
• VORP - Value Over Replacement Player.  The number of runs the pitcher prevented compared to a replacement level pitcher (i.e. a typical emergency starter or long man in the bullpen, who is worse than an average pitcher).

In setting the positional average and replacement level averages for each player, every game and position that the player appeared in is weighed into the equation. E.g. if a player played 20 games at shortstop and 20 games at third base, his positional average would be halfway between the average SS and 3B production. Pinch hitting and pinch running appearances are compared to the PH/PR league averages as well.

A player is listed at the position he appeared most often at. In the case that two or more positions are tied for the most games, the player is listed multiple times (once at each position). However, unlike last year, his positional average is a composite of all of his actual positional appearances, rather than just the most frequent, so his actual VORP should not change across the several listings. This is arguably a minor bug that I may clean up at some point during the year.

Replacement-level delta is set at 70 points of OPS below league positional average (based on previous studies I've done, but have not published -- I may finally get around to it this year). The same delta is used for all positions (this is a possible area for future research).

For pitchers, VORP is defined as the number of runs a pitcher surrenders below what a replacement level pitcher would have given up in the same number of innings. Replacement level is set at +1.00 above the league average RA.

Park factors being used are the 3-year park factors (for 1999-2001) reported in the 2002 STATS Major League Handbook.

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Copyright 1997-2001 by Keith Woolner. All included authors retain the copyrights to their original works.