My writings about baseball, with a strong statistical & machine learning slant.

Wednesday, February 17, 2010

Firemen are soooo predictable! (addendum to 'Fastballs for Dinner')

Silly me. I was comparing starters to all pitchers. We all know that there are three kinds of pitchers: starters, relievers and Joba Chamberlain.

I isolated the starters with a simple 100 IP cutoff. I can similarly isolate the relievers by requiring no more than 6 starting innings pitched. This captures 86% of the relief innings, with less than 1% contamination by starter innings.

Graphs for relievers are below:

There is not a whole lot of difference between the known relievers and the "all pitchers" figures. However I can't help note just how similar all lefty relievers' repertoires really are. If this is evolution, I hope evolution doesn't happen to the general pitcher population.

Then again, the data I'm using does not take account of two-seam fastballs or of sinking fastballs. But still, all of the crafty lefties I can think of are starting pitchers. As I mentioned in an earlier post, there has been a steady increase of lefty starters in the past decade. So maybe clubs are doing a good job of getting their best lefties into the rotation. The lefties who throw smoke but can't learn a pitch other than a slider end up in the bullpen.

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