A common complaint of people who do not follow sports is that there are too many statistics to keep track of. A more detailed argument would suggest that statistics do cause problems because there is no true way to measure one player's total performance against another, and how that performance impacts his team overall.
But now, with the ingenuity of MIT graduate Keith Woolner, Major League Baseball has a statistic that is the proverbial "stat to rule them all". Well, almost. This end-all statistic is Value Over Replacement Player, or VoRP.
What is Value Over Replacement Player - VoRP?
In short, VoRP calculates how many runs a batter adds to his team's total throughout the course of a season over that number which an "average major leaguer" would contribute. For those who don't hit, VoRP is tailored to measure the converse of what it measures for hitters-the number of runs a pitcher prevents from scoring over those that an average pitcher would allow to score.
For each version of VoRP, there are markedly different formulas that determine each player's rating.
Calculating Hitter's VoRP
As stated earlier, the significance of a hitter's VoRP embodies the number of runs he contributes beyond what a major league "replacement-level"-e.g. average-player in the same postion would contribute if that player saw the same percentage of a team's plate appearances as the other hitter. Note that plate appearances are used in this formula instead of at-bats, as plate appearances represent the true, total number of times a hitter goes to bat whereas sacrifice situations or walks do not factor into a hitter's at-bat statistic.
When calculating a hitter's VoRP, the first step necessary is to determine what the "replacement-level" is for a certain percentage. For most positions, that level is roughly 80% of the league average in terms of runs per out. But two anomalies exist among the positions at the catcher, first base, and designated hitter positions. At catcher, the constant for replacement-level "R" is roughly 75% since a catcher's primary responsibility is geared toward the defensive side of the game. On the contrary, first basemen and designated hitters (obviously) shoulder more responsibility offensively rather than defensively, so their replacement-level constant is about 85%.
From there, a formula is used to determine the replacement-level averages of players by calculating the points "P" to subtract from a position's average batting, on-base, and slugging percentages. To calculate P, you substitute the R value for the respective position in the formula below, alongside the three batting statistics.
After calculating P, you subtract that number from each one of the three stats to find the replacement-level averages for a player. This gives us a benchmark for what a replacement-level player's stats should look like and how starting players' numbers match up to them.
To calculate the true VoRP, we must use the bread and butter of all baseball statistics-runs and outs. First, you must multiply the league's average runs per out by the total number of outs a player made in a season giving us the number of runs an average player created with that number of outs to work with.
Next, that number of runs is multiplied by the replacement-level performance percentage mentioned above resulting in the number a replacement-level player could be expected to "create". Those runs created are then subtracted from a player's number of Runs Created to determine his VoRP rating.
To calculate a hitter's Runs Created rating, a basic formula will suffice, where one multiplies a hitter's total bases by the sum of his hits and walks, whose product is divided by the sum of a batter's at-bats and walks.
Calculating Pitcher's VoRP
On the other side of the equation is how a pitcher's VoRP is calculated. This measures how many less runs a pitchers allows to score than what a replacement-level pitcher would allow, essentially the opposite of what a hitter's VoRP compares between players.
For pitchers, the replacement-level must be found first in order to be used in calculating the VoRP. The replacement-level of a starter is calculated by multiplying the league's average runs allowed per game by 1.37 and then subtracted .66 from that total.
A reliever's replacement-level is determined by multiplying the league average of runs allowed per game by 1.7 and subtracting 2.27 from that product, to account for the discrepancy in innings pitched between starters and relievers.
- Starters: RL = 1.37 x League RA - 0.66
- Relievers: RL = 1.7 x League RA - 2.27
From there, VoRP is calculated by subtracting a player's run's allowed per game from the replacement-level runs allowed per game, dividing that total by nine, and then multiplying the dividend by the player's number of innings pitched for the year.
Final Look at VoRP
An interesting aspect of VoRP is that every ten runs created, or every ten points of VoRP, is equivalent to one win added to your teams total. As a result, a players VoRP rating can be divided by ten to get a rough estimate of what his Wins Above Replacement Rating is.
Similar in form to the Player Efficiency Rating ( Ultimate Guide for PER) developed by John Hollinger for the National Basketball Association, VoRP gives fans, league executives, and MVP/ Cy Young voters one number to use when considering who are the best players in the game, and those that can best help their team.
Bear in mind, like WAR, this statistic accumulates over the course of a single season so the numbers are much lower than they will be at the end of the year.