A method of estimating of a team’s True Talent record based on runs scored and runs against. In a large enough sample (i.e. when the team has faced teams whose true talents average out to roughly .500), this will be equal to the team’s estimated winning percentage against a .500 team. It has the following formula:
Pythagorean record formula
The exponent of 2 can be replaced with a better number—commonly around 1.81—or a dynamic exponent as determined by a formula like Pythagenpat.
There was a throwaway comment about true talents averaging to .500 in the first paragraph. That is not quite accurate. Phil Birnbaum astutely points out the difference between how a team would perform against a .500 team and how a team would perform against a sample of teams who average to a .500 true talent. Pythagorean record tells you the latter. In baseball, this difference is not massive, but it still exists and it is important to keep in mind.