OWP

From Wiki Gonzalez

OWP = Offensive Winning Percentage. This statistic tries to capture how often a team with league average pitching and defense but 9 clones of a given player batting would win against a league average team.

Deriving this based on the Pythagorean formula and RC we get:

PlayersTeamRA = LeagueRunPerGame
PlayersTeamRS = RC/27

By the Pythagorean formula:

PlayersTeamWin% = (PlayersTeamRS^2) /(PlayersTeamRS^2 + LeagueRunPerGame^2)
                = (RC/27^2) / (RC/27^2 + LeagueRunPerGame^2)

A league average player by definition has a .500 OWP. Barry Bonds's 2004 season is the best ever OWP, coming in at .958.