Posted by: Peter | March 31, 2010

Sabermetric Classics

Tom Tango had a nice little post about an old Bill James stat called “Secondary Average”, which linked to a discussion here. The formula is just:

As Tango puts it, this is “everything that batting average isn’t”. Batting average counts singles and extra base hits the same and ignores other means of gaining bases (like walks and stolen bases). Secondary average includes all these “missing bases”.

It turns out that across the league, batting average and secondary average have roughly the same average value, but secondary average is more consistent, varies more between players, and isn’t closely associated with batting average. This makes it a neat stat, although it’s of mostly historical interest today–we have fancier and more accurate ways of measuring production. Still, I thought it would be fun to compare the batting average and secondary average of this year’s primary Twins hitters. I used the above formula, except that I also included hit batters.

First, here’s how they did for 2009:

The line indicates where a hitter would fall if his batting average and secondary average were equal. You can clearly see how Twins hitters are grouped into different types of hitters. There are the power hitters, who contribute more bases than their batting average would indicate. There are the “empty batting average” guys who contribute little beyond singles. There are guys like Nick Punto and J.J. Hardy, who just sucked. And there’s Joe Mauer, who’s just all-around great at everything.

Looking at these players’ career numbers shows mostly the same patterns:

Everyone is closer together, as variation is evened out in the larger sample size. Everyone except Jim Thome, that is, who shows just how awesome he is at doing the things that aren’t hitting singles.  And with the start of the season less than a week a way, I can’t wait to see him start doing those things in a Twins uniform.


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