August 9, 2007

IT ALL EVENS OUT IN THE LONG RUN:

D-Backs coming through (Nick Piecoro, 8/06/07, The Arizona Republic)

t's understandable why some throughout baseball are wondering how, exactly, the Diamondbacks, at 63-50, own the second-best record in the league entering the final eight weeks of the regular season.

On the surface, it would appear things don't add up.

In fact, based solely on run differential, they are among the biggest overachievers in baseball history.

Legendary statistician Bill James developed a "Pythagorean Theorem" that, by plugging a team's runs scored and runs allowed into a formula, showed a striking correlation between the differential and a team's record.

The Diamondbacks have scored 467 runs and allowed 496. Using James' formula, they would be expected to have a .470 winning percentage.

In actuality, they have a .558 winning percentage, a .088 point gap that would be the second-largest discrepancy between actual record and expected record in baseball history.

According to David W. Smith of Retrosheet .org, only the 1905 Detroit Tigers, who outplayed their expected record by .091 percentage points, had a bigger discrepancy.

So how are the Diamondbacks doing it? General Manager Josh Byrnes has some ideas, and they start with his team's ability to win one-run games.


Except that, as Bill James has also shown, your record in one-run games isn't a reflection ability but of more random factors.

Posted by Orrin Judd at August 9, 2007 11:56 AM
Comments

They have a tendency as well for their pitching staff to disintegrate during bad games. They ended an 8 game win street by being whacked 14-0. And their offense is so wobbly that they almost never win games by similar margins.

Posted by: Brandon at August 9, 2007 2:04 PM

It also helps that the NL is the parity league. There are no great or even very good teams in the league to push the Diamondbacks around. The Phillies have the best run diff in the NL at an underwhelming +55. San Diego is the best team in Arizona's division, and they only have a run diff of +47. Even a really bad team like the Cards can hang around in semi-contention with a run diff of -98.

By the way, James' old Pythagorean forumla has been super-refined. The cognoscenti now use an exponent of 1.83 instead of plain old 2.

Posted by: Casey Abell at August 10, 2007 7:51 AM
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