Wins Above Team
Wins Above Team (WAT) refers broadly to any number of statistics that attempt to separate a pitcher's performance as measured in won-loss record from that of his team, or specifically to the first such effort, that of Ted Oliver in his 1944 pamphlet Kings of the Mound. It is closely related to Normalized Winning Percentage.
Oliver first calculated the team's winning percentage without the decisions of the pitcher in question (the teammate's winning percentage, or "Mate"), then simply subtracted Mate from the individual's Winning Percentage and multiplied by the number of decisions for the pitcher:
Mate = (Team Wins - Wins)/(Team Wins + Team Losses - Wins - Losses)
WAT = (W% - Mate)*(W + L) = W - Mate*(W + L)
The result is the number of games won by the pitcher in excess of those an average teammate would have recorded.
Bill Deane Modification[edit]
Bill Deane revised the formula, and Total Baseball included computations of WAT by Deane's method. Deane's modification recognized that the potential room for improvement on Mate depended on high it was. For example, a pitcher who raised his team from .500 to .550 had made the same percentage gain on what was possible (.050 out of a possible .500, or 10%) as one who raised his team from .400 to .460 (.060 out of a possible .600, also 10%). Thus, for pitchers with W%>Mate:
WAT = (W% - Mate)/(2*(1 - Mate))*(W + L)
For those with W%<Mate:
WAT = -(Mate - W%)/(2*Mate)*(W + L)
Rob Wood Modification[edit]
Rob Wood, in an August 1999 By the Numbers article, revisited the topic, and proposed a new formula for Normalized Winning Percentage, and by extension WAT. Wood's approach was to assume that the deviation of Mate from .500 was due in equal share to their offense and pitching. Since the pitcher in question does not see his W% increase as a result of what his fellow pitchers do, the standard for measuring his value should be half of the deviation from .500. Wood's approach led to the following formula for WAT:
WAT = (W% - (Mate + .5)/2)*(W + L) = (W% - Mate/2 - .25)*(W + L)
