Pythagorean Theorem

The Pythagorean Theorem is a means of estimating the winning percentage of a team based on their runs scored and allowed developed by Bill James, and so named because of its resemblance to the Pythagorean Theorem of geometry.

The basic expression of the Pythagorean Theorem is:

WPct = RS^2/(RS^2 + RA^2)

Or, equivalently:

W/L = RS^2/RA^2

James later suggested that an exponent of 1.83 would be more accurate. Later research, most significantly by Clay Davenport and David Smyth, has resulted in exponents that vary depending on the total runs scored and allowed in a given team’s games.