The Tigers Have Been Kicked in the Pythagoras

It’s been a dismal and deflating season in Detroit. The Tigers, who entered the year as favorites to win the AL Central after signing both Framber Valdez and Justin Verlander in February, played middling baseball through the first five weeks of the season before hitting the skids in May, at one point losing 16 out of 18 games. Instead of loading up for the stretch run ahead of the August 3 trade deadline, they dealt away both Tarik Skubal and Casey Mize to other contenders. While the team has actually outscored opponents by 47 runs (610 to 563), the Tigers are currently 11 games below .500 at 64-75, and in danger of making some dubious history by falling short of their Pythagorean-projected win total by the largest margin of any Wild Card-era team.
Misery loves company, and the Tigers are not alone in undershooting their target. The Giants, who at the outset of the season looked to have a reasonable chance of claiming a Wild Card berth, are not only 24 games below .500 (58-82) but in danger of falling short of their BaseRuns-projected win total by the largest margin of any team since 2002.
If you’re not familiar with either of these concepts, a Pythagorean projection is one of the most enduring Bill James creations, introduced in his self-published 1980 Baseball Abstract. James showed that simply by knowing a team’s runs scored and runs allowed, one could estimate its winning percentage with a reasonable degree of accuracy via the formula Winning % = RS^2 /(RS^2 +RA^2). The use of the squares, reminiscent of the Pythagorean formula to calculate the length of a right triangle’s hypotenuse, is what gives the stat its name. Further refinements by James and other sabermetricians showed that using a slightly smaller exponent increased the accuracy of the estimate. The Pythagenpat formula, where the exponent itself is a function of the scoring environment via the formula X = ((RS + RA)/G)^0.287, is the one we use for our Projected Standings pages, which now have all major league seasons dating back to 1871 (damn those underachieving Rockford Forest Citys). Read the rest of this entry »






