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Pythagorean Baseball

Anybody who has read this blog for a while knows that I don’t rely too heavily on stats. I’m into traditional stats and like to read about stats and sabermetrics and the like but I think people these days tend to over analyze things based on stats. So it was kind of odd for me to be reading Dayn Perry’s “Winners: How Good Baseball Teams Become Great Ones (And It’s Not the Way You Think)”. This is an excellent book that does a statistical analysis of winning teams since the early 1980s and, based on the results, concludes what qualities it takes to be a winning team.

One of the stats touched upon very late in the book is a Bill James creation called Pythagorean Method. (It takes it’s name from geometry’s Pythagorean Theorem since it’s notation is similar.) This method attempts to predict a teams winning percentage based on the runs they score and the runs they allow. The formula for this stat is as follows:

Runs Scored2/(Runs Scored2+Runs Allowed2)= Winning Pct.

I was curious to see how this stat played itself out in reality so I did a quick analysis of the Mets, Phillies and Braves to see how they were doing based on this statistic. The results are as follows:

Team Runs
Scored
Runs
Allowed
Pyth.
Pct
W L Pct.
Mets
343
275
.609
41 23 .641
Phillies
324
326
.497
33 32 .508
Braves
330
347
.475
30 36 .455

The theory goes that if a teams actual win percentage is above their Pythagorean win percentage then they are playing above expectations. If it’s below then thay are playing under their expectations. So, according to this, the Mets are playing above expectations, the Braves are playing below expectations and the Phillies are playing close to expected (but slightly below). That would mean that according to Pythagorean Method this race will tighten up a bit. It’ll be interesting to see how Pythagorean Method predicts what will happen.

Just for fun I plugged the Yankees into this formula and compared to the Mets.

Team Runs
Scored
Runs
Allowed
Pyth.
Pct
W L Pct.
Mets
343
275
.609
41 23 .641
Yankees
366
294
.608
37 26 .587

According to this the Mets and Yankees should have identical records but the Yankees have been under performing. Interesting. Stay tuned.

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Comments

[…] With each Major League team having played over 100 games thus far this season I felt like now would be a good time to revisit the discussion on Pythagorean Method that I started in June. Back then the teams had played over 60 games. With about 40 more games upnder their belts let’s see if the theory holds true. […]

[…] at these teams had me thinking about how they would fair in Pythagorean terms. I’ve written before about Pythagorean Method, the Bill James creation that tries to predict winning percentage based on […]

mostly mets,
Hi! if you want see the pythagorean win shares in graph form for the mets, phi, atl or every team for that matter. click http://www.baseballinvestor.com

— as a side-note, i’d be more than happy to get you some gifs (pictures)for your site.

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