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Pythagoras Theorem and Baseball

Posted May. 28, 2008 03:57,   

한국어

Master of baseball stats, Bill James, came upon a new formula while tallying the records of major league teams in the early 1980s. He found out how to calculate the winning rates of a team with total runs scored and total runs allowed.

Applying the Pythagoras Theorem, which is summarized as “the square of the hypotenuse of a right triangle is equal to the sum of the squares on the other two sides,” James noted that the winning percentage is obtained by dividing the square of total runs earned by the sum of the squares of the total runs scored and total runs allowed. This is what is casually termed as the winning percentage of Pythagoras.

Looking into the records of professional Korean baseball team, using this theorem, SK and Lotte stand out among the eight teams.

As of Monday, SK has won 31 games and lost 16, amounting to 0.660 in winning percentage, while its Pythagoras percentage is 0.592 or 0.7 points higher than the normal rate. When the Pythagoras figure is multiplied by the number of games, SK should have won 27.8 games, statistically. But the team has won 31, a result that is three games higher than the prediction based on the “baseball Pythagoras theorem.”

On the other hand, Lotte came two games short, notching up 25 games in reality.

Purely in terms of the formula, Lotte stands at the top with its unrivaled team ERA of 3.63 and second best team batting rate of 0.275.

Baseball experts attribute, as in most cases, the “better-than-estimated performance” of SK to its strong bullpen, since the strong pitcher pool does not allow too many runs. SK is not an exception. By contrast, Kia won 20 games (22.4 calculated) and Lotte lost many close games despite its numerous lopsided wins.

Arizona Diamondbacks general manager Josh Byrnes once said, as vice president of the Boston Red Sox, the Pythagoras formula was useful in setting up strategies later in a season. In other words, when a team’s actual performance exceeds the calculated figure, the team is likely to continue the winning curve, while a team with reversed records will face the opposite in most cases.

But a theory is just a theory. We hold our breath and wait to see whether “mathematical leader” Lotte can beat “actual leader” SK.



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