Offensive Winning Percentage

Offensive Winning Percentage (OWP) is a Bill James statistic that measures the rate of offensive performance. A player's OWP is the winning percentage that the Pythagorean Theorem would project for a team that scored runs at the rate the player created them, but allowed a league average number of runs.

The formula for OWP is:

OWP = (RC/Out)^x/((RC/Out)^x + Lg(RC/Out)^x)

where RC is Runs Created and x is the Pythagorean exponent used (usually 2).

Run estimators other than RC can be used in conjunction with OWP, although dynamic estimators are more compatible due to the team perspective of the method. For a period of time, James replaced the league average of runs created per out in the formula with the average of the runs scored and allowed by a player's team per game (i.e., if his team scored 6.00 runs per game and allowed 5.00 runs per game, the "opponent" in the Pythagorean calcuation would be at 5.50). This was an attempt to adjust for context, but was later discarded.

It often needs to be emphasized that OWP assumes that the defense is league average, not of equivalent quality to the offense. This sometimes becomes a point of confusion when OWP is used to define the replacement level. James set the replacement level at a .350 OWP, which means that a team with an average defense and a replacement level offense would be expected to win 35% of their games.