Thursday, May 24, 2007

Great Stuff on Fielding

I caught part two of John Walsh's defensive measurement series for infielders today. Today's article and part one seem to me like ground-breaking stuff in regards to measuring how well infielders are performing defensively. The graphs he has created uniquely blend quantitative information with a physical plane that resembles the visual picture one would have looking at the infield from behind home plate. From this vantage point a person can quickly get a feel for where a particular team's defense is weak, strong or average. They'll be able to tell if their shortstops are good at going to their left or if their third baseman can't grab balls down the line.


One of the more interesting finds in the study follows.


This graph, like its title indicates, exhibits where ground balls are hit. The horizontal axis can be read from left to right like one would look from 3rd base over to 1st base on a baseball diamond. Note the dearth of ground balls up the middle between angles 40 and 60. As Walsh points out,

I don't know about you, but I find this plot fascinating (I need to get out more, I know). First of all, I wasn't expecting this shape to the ground ball distribution. I expected to see two humps around the shortstop and second base positions, but I am surprised to see that double-peak structure on the left side.

I imagine that the more statistically inclined major league teams have had proprietary defensive measurement/evaluation systems like this dating back to the early part of this century or maybe even back into the 90's.

Walsh's study appears to be the start of a series of articles where he will continue to add tweaks to his system based on different playing variables that help to determine where ground balls on the infield ultimately go and how they are handled by major league infielders.

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