A Note on the Pythagorean Theorem of Baseball Production

Recent analyses of baseball managers' performances have employed the so-called 'Pythagorean Theorem' of baseball. This 'theorem' states that the ratio of wins to losses can be approximated by the square of the ratio of team runs scored to opposition runs scored. Recent publications assume this approximate relationship can be used to evaluate managers; implicit is the additional assumption that the Pythagorean relationship constitutes a production process. It does not. This paper derives the exact relationship between the wins, losses, runs scored and runs allowed. The result is an identity. We conclude that application of the 'Pythagorean Theorem' for manager evaluation is inappropriate. © 1997 John Wiley & Sons, Ltd.