September 27, 2012

Baseball Prospectus News

Announcing the PITCHf/x Matchup Analysis Tool

by Dan Brooks

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Just in time for the playoffs, we’re bringing you a way to get detailed information on every batter-pitcher matchup via our new Matchup Analysis Tool, found here and also accessible through the “PITCHf/x Matchups” dropdown link on the “Statistics” tab of the navbar at the top of the page.

The Matchup Analysis Tool allows you to select a particular pitcher and batter and visualize every time they’ve faced each other during the PITCHf/x era (partial 2007, complete 2008-2012). As an example, let’s take Prince Fielder vs. CC Sabathia.

The first link on the page that appears is important: if you find an interesting matchup and want to share it with your friends, right click the “Direct Link to this Matchup” link and copy that link’s location. It will automatically bring your friends to the page you’re looking at.

From the first table (reproduced directly below), you can see that Sabathia has thrown Fielder 19 Fastballs, two Sinkers, and 21 Sliders. On the bottom left, you get a log of each time they’ve squared off, along with a date, result, Pitch Tags from the PITCH INFO database that drive BrooksBaseball.net, and pitch speed.

On the right-hand side of the page, you see two graphs. One of those shows all plate locations in their matchups, coded by pitch type.

To download a high-res version of that chart, click the green arrow in the upper right corner. You can also do some fancy things with it (which is produced with the Highcharts Package)—for example, you can click any of the individual pitch types and hide them, so you can get a picture (if you want) of CC’s sliders alone to highlight to yourself (or your readers) how he’s approached Prince with that particular pitch.

This is very useful when you’re drilling down on a messy matchup that has occurred many times—for example, if you want to highlight the location of Jon Lester's changeups to Derek Jeter.

You can also make this chart show just one individual plate appearance, which is useful for those of you who would normally show things to your readers by finding the individual matchup in Gameday and then taking a screenshot of the page. If you click one of the dates next to the individual plate appearance, it will bring you to a page that shows a graph for only that PA, with several additions made:

First, the title of the chart will change to show the result, which can be useful for your readers (or yourself!) to remember what happened in each at-bat that you pull. Second, the pitch types are now labeled by pitch sequence: we can see that Sabathia started Prince with two inside fastballs, followed by a slider down and away, etc. Third, if you mouse over any of the individual pitches on that plot, it will tell you the result of that pitch (swing, line drive, ball, etc.) and whether or not the batter swung. So, you get all the Gameday information that you might get from an individual screenshot, but you get it in a more easily grokkable format. To clear this single plate appearance filter, simply click the link on the left side of the page to “Remove Single PA Filter”, which will bring back the main plot.

Last, we have a chart in the bottom right that will show how Sabathia approached the start of the plate appearances by Fielder, along with his first-pitch percentages by pitch type against all left-handed hitters (or, if we were to have selected a right-handed hitter, against all RHH):

We are still developing this tool internally, and so we’re always open to suggestions to make it more easily navigable, make the data clearer, or change the presentation style. Our goal is to help our own readers, bloggers, and writers more easily dissect the batter-pitcher matchups that make baseball so much fun to watch.

Here's another link, since scrolling up is hard.

Dan Brooks is an author of Baseball Prospectus. Follow @brooksbaseball
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