From Wiki
Jump to: navigation, search

Value Over Replacement Player is a metric invented by Keith Woolner and popularized by Baseball Prospectus. It measures the runs a player is responsible for above and beyond what a hypothetical replacement player would do.

VORP as calculated by Baseball Prospectus uses Marginal Lineup Value, derived from Runs Created as its run estimator for hitters. Other run estimators could be used.

Replacement Level[edit]

The replacement level of VORP is supposed to correspond with a team of a .271 winning percentage. Many have criticized this as being too low.

  • Tangotiger: Is this true? Looking at the levels below, it doesn't look like it's a .271 team. It looks more like a .300 or higher team. In any case, I'm not sure anyone has criticized VORP replacement level as too low. VORP is not WARP. Either the .271 needs substantiation, or this paragraph should be removed.
  • Colin: [1]
  • Tangotiger This is inconsistent, since the OPS that Woolner is showing is 100 points below the league average, and not the 70 points being described otherwise. Please do not delete this discussion until this is resolved.
  • PatriotWe know that the offensive replacement level in VORP is around 80%, with replacement players considered to be average fielders. We also have the formulas for pitcher replacement level below. Last year in the majors, 64.8% of innings went to starts and 35.2% to relievers. The overall RA was 4.83, so the starter level is 5.96 and the reliever is 5.94 (incidentally, there's a criticism of VORP that can be added). So the overall pitcher replacement was 5.95, which is 123% of the league average. .8^2/(.8^2+1.23^2) = .297. So I think it's safe to say that the replacement team W% is ~.300

For position players, replacement level is calculated as either 80% of the league average production at that position, or 35 points of OBP and SLG below the league average. (Due to the defensive premium at the position, catchers are given 75% of positional average as the replacement level; due to the offensive demands of the position, first basemen and designated hitters are given 85% of positional average as replacement level.)

For pitchers, replacement level was originally the league Run Average plus one. In Baseball Prospectus 2002 the formula was updated to use different replacement levels for starters and relievers:

Starters: Replacement level = 1.37 * League RA - 0.66 Relievers: Replacement level = 1.70 * League RA - 2.27

VORP for position players[edit]

A position player's VORP is simply his MLV minus the MLV score of a replacement player projected out to the player's number of plate appearances.

VORP for pitchers[edit]

A pitcher's VORP subtracts his RA from the RA of a replacement level pitcher, divides by nine and multiplies by innings pitched.