Bill James’ discovery of the Pythagorean Win Expectation is one of the cooler findings of sabermetric research. You can read up on the details by following the given link. In short, what James found is that one can get a pretty good approximation of a team’s winning percentage given only their runs scored and allowed by using the following formula:

It works remarkably well, and more recent versions like PythagenPat are even more accurate. I won’t repeat the basics, which can be looked up elsewhere. Instead, I want to address the occasional misuse of the formula for building narratives of teams being better or worse.

Read the rest of this entry »