Evaluating Pitcher Accuracy with Catcher Charting

May 19, 2011
Today, I’m excited to share with you one of the new things we’ve been working on at Baseball Info Solutions. 

In addition to our normal pitch charting efforts, last year we started charting the catcher’s target on each pitch.  Where does the catcher place his mitt prior to the pitch as a target for his pitcher?  This data leads to all kinds of analysis that can be done.  For example, as we’ll show here, we can determine how one pitcher compares to another in terms the accuracy of their intended pitch location. Or, at least the catcher’s intended pitch location. In the examples below, we’ll look at each pitcher’s complete repertoire but this information can also be broken down by pitch.  How does a particular pitcher locate his fastball?  How about his curve?

Let’s take a look at Roy Halladay, who is famous for his pinpoint control.

The chart on the left is a scatter plot of all of Halladay’s pitches this season.  To generate this chart, we center the catcher’s glove at the point (0,0) and plot each of his pitches (the green dots) relative to the glove.  The numbers on the axes represent how many pixels in each direction Halladay was off by on a particular pitch.  As you can see, Halladay has a high concentration of pitches thrown right to the target.

To the right of the scatter plot is a breakdown of Halladay’s pitches by distance from the catcher’s target.  The breakdown separates Halladay’s pitches into four categories: Closest to Mitt, Close to Mitt, Far from Mitt, Farthest from Mitt.  Picture these categories as concentric circles around the catcher’s mitt.  We set the MLB average as having 25 percent of pitches in each zone and the bar graph indicates that Halladay is much more accurate than the average pitcher.  Only 17 percent of his pitches fall in the Farthest from Mitt category.

As opposed to Halladay, who has only walked 11 batters in 69.1 innings this season, Reds pitcher Edinson Volquez leads baseball in walks with 34 in 48.1 innings.  His charts paint a much wilder picture than Halladay’s.

Only 19 percent of Volquez’s pitches are categorized as Closest to Mitt, as opposed to Halladay’s 31 percent. 

One final pitcher to evaluate is Red Sox knuckleballer Tim Wakefield. His chart is a clear demonstration of how neither the pitcher nor the catcher (and obviously not the batter) knows where a knuckleball is going. 

Wakefield’s Closest to the Mitt percentage is a mere 7 percent compared to the 44 percent of his pitches that are charted Farthest from Mitt.  In 2010, Wakefield had 12 percent of his pitches Closest to the Mitt.

This type of analysis can also be done relative to the hitter.  For example, where do the Tigers like to pitch David Ortiz when they get to an 0-2,1-2, or 2-2 count on him?  Answer: low and away about two-thirds of the time, low and in the rest.  There were 40 such pitches since 2010 and about two-thirds of them (26) were targeted on the low-outside corner, with the rest low and inside.



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