View Full Version : Question about run differential

07-07-2008, 08:31 PM
I've noticed that The Cubs have a run differential (runs scored v. runs given up) of +102, by far the best in baseball. I haven't had much exposure to this stat in baseball and I'm wondering if any of you can tell me if there has been value in analyzing it in the past . . .

thanks in advance.

07-07-2008, 08:38 PM
Of course. It has to do with pyth record. Statisticians can predict how many wins or losses you should have according to the run differential. It helps to let you know what teams are more lucky then others. For instance AZ last year was very lucky, accord to the run differential, they should have had about 9 wins less last year (i really can't remember how many fewer wins they should have had but it was a good amount)

07-07-2008, 10:24 PM
Have you ever heard of the Pythagorean Expectation?

Basically it's a statistical formula for predicting winning percentage based on runs scored vs. runs allowed.

(runs scored)^2 / [(runs allowed)^2 + (runs scored)^2] = winning %

for the Cubs it would be: (475 X 475) / ( 373 X 373 + 475 X 475) = 225625 / (139129+225625) = .618, or a 61.8 predicted winning percentage.

The Cubs have a 53-36 winning percentage right now, and the 61.8 winning % obtained by the formula predicts a 55-34 record for our Cubs which is pretty accurate.

or check out this wikipedia article:


also, Baseball-reference.com says that the more revised Pythagorean expectation raises the runs scored and runs allowed to the 1.83 power instead of the 2nd power, and that this is slightly more accurate. Actually using this formula instead predicts a 54-35 record for the Cubs which is even more accurate.

07-07-2008, 11:24 PM
thank you both, that's very helpful information.