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Thursday, January 18, 2007

Myths and Excellence

My column this week on Baseball Prospectus, published this morning, is titled "The Myth of the Golden Age" and explores the reasons why, and the demonstration of, an increasing level of play over time. In addition to reviewing the arguments the late Stephen Jay Gould put used in his 1996 book Full House: The Spread of Excellence from Plato to Darwin, I take a quick look at how the hitting of pitchers relative to position players (inspired by the comments of fellow SABR member Stew Thornley) has changed over the course of time and how it is arguably a demonstration of increasing excellence under an evolutionary model.

One of the interesting aspects of that discussion involves how the slope of the relative OPS of pitchers (defined very loosely as players who appears in more than one game as a pitcher in a given year) seems to have changed after World War II. The following two graphs illustrate this change using linear trend lines.





You'll notice that the slope of the line in the first graph is over twice that of the second. This supports nicely the research by Gould on decreasing variation in batting average and Nate Silver's research in Baseball Between the Numbers that shows the game stabilizing after 1940.

3 comments:

Anonymous said...

Dan:
Really excellent article. I'd like to see you take the pitcher data further to actually quantify the improvement in player quality. Just looking at your graphs, it would appear the average hitter today is far better even than his 1946 equivalent. Since then, the average OPS has increased about 20%, meaning a 40%+ improvement in run production. Of course, that assumes today's pitchers are as good hitters as the 1946 pitchers, an assumption that certainly can be challenged. But if that's true, Wagner might really be Neifi Perez today.

And of course if we know how much better the hitters are, we can estimate the pitcher improvement as well.

Tangotiger said...

Dan,

Rather than use a loose definition of a pitcher, he're a pretty quick way to do it:
http://www.insidethebook.com/ee/index.php/site/comments/database_hacks/

After reading the main blog entry, look at comment #4.

And, the result of all that is posted in comment #5

Tom

Dan Agonistes said...

Thanks for that. I've used something similar in the past but I like your query better.

I used this loose definition of a pitcher for another reason as well. One of Gould's arguments deals with increasing specialization in the game and using this definition allows me to show the evolution of specialization in the pitcher position (both as pitchers focused more on pitching, especially as the mound was moved back to 60'6" in 1893 but also with the increase in relief specialization driving down the percentage of plate appearances consumed by pitchers).