## Comparing Plate Discipline: Visually and Numerically

Here at Fanpraphs, we have plate discipline recorded for each hitter going back to 2002. These values are useful, but how do these values translate into the exact strike zone that a players uses? Today, I decided to look at how the visual and numerical plate discipline compares for three players, Brett Gardner, Vladimir Guerrero, and Torii Hunter.

I chose these three players because they each had varying degrees of plate discipline according to their Swing% (Total percentage of pitches a batter swings at). Out of all qualified batters in 2010, Brett had the lowest Swing% while Vlad had the highest. I also wanted to have a player with an average Swing%, and Torii was picked. Here is a chart of their 2010 Swing% values:

Now, here is how each of the three players swung at pitches during the 2010 season:

The scale equals the number of pitches swung at (contact or no contact) divided by all pitches thrown in that part of the plate. I am looking at 6โ square boxes and have a zone for both left handed and right handed pitchers. The view is from the catcher’s perspective looking at the pitcher. The box is the MLB regulation strike zone and the circle is used just for reference.

Brett Gardner (Swing% = 31.0%)
vs. Left Handed Pitcher

vs. Right Handed Pitcher

Torii Hunter (Swing% = 46.5%)
vs. Left Handed Pitcher

vs. Right Handed Pitcher

vs. Left Handed Pitcher

vs. Right Handed Pitcher

The visuals nicely back up the numbers. For pitches in heart of the strike zone, Brett rarely swings at any pitch over 60% of the time. Vlad on the other hand is swinging at pitches over 90% of the time depending on the pitch’s location. Finally Torii seems to have a nice understanding of the strike zone.

For comparison sake, here is each player’s personal strike zone dating back to 2007:

Brett Gardner
vs. Left Handed Pitcher

vs. Right Handed Pitcher

Torii Hunter
vs. Left Handed Pitcher

vs. Right Handed Pitcher

vs. Left Handed Pitcher

vs. Right Handed Pitcher

I hope having the visual zone to go with the numerical zone will give you a better perspective of a player’s strike zone. I will be doing more of these comparisons in the future, so let me know if you have any questions.

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Jeff writes for FanGraphs, The Hardball Times and Royals Review, as well as his own website, Baseball Heat Maps with his brother Darrell. In tandem with Bill Petti, he won the 2013 SABR Analytics Research Award for Contemporary Analysis. Follow him on Twitter @jeffwzimmerman.

### 14 Responses to “Comparing Plate Discipline: Visually and Numerically”

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1. Joe Crede says:

Feel free to delete this comment immediately, just to let you know you started with here at fanpraphs

2. SF 55 for life says:

wow these are really cool. excellent work. I always wondered how much plate discipline Brett Gardner has. It seems to me like he is pulling a Luis Castillo and just flat out not swinging until he has two strikes.

3. Matt says:

Brett Gardner really really likes that low and away pitch it seems (or is it low and in?)…

• WY says:

Good question. Are these charts from the pitcher’s POV or from the hitter’s?

• Jeff Zimmerman says:

As stated in the article:

The view is from the catcherโs perspective looking at the pitcher.

With Gardner’s one zone, it is probably just a couple pitches in that zone. From now on I am going to add in a league average value to each box to each areas like that one from showing up.

4. PiratesBreak500 says:

I found this really useful, thanks. Seeing them side by side makes a lot more sense than just one alone.

5. dcs says:

These graphs should help dispel the notion that plate discipline is all about not swinging at bad pitches. It’s also about not letting fat pitches go buy for free, as Gardner (and L Castillo, and many others) seem to do.

The graphs are kind of cool, but I’d much rather see a bit more granular version of OSwing and ZSwing, using 4 categories instead of two. Divide ZSwing into ‘within the circle’ and ‘outside the circle’, and OSwing into 3″ or less outside, and further than that. The size of the fat pitch circle and the ‘close but outside’ categories could be determined just by looking at how the data shakes out.

If fangraphs can do that, it would be really insightful.

6. Hank says:

Nice work…

It might also be useful to look at count (though that would probably lead to issues with sample size). Maybe a look at 2 strikes vs <2 strikes (and ignoring the # of balls in the count so the samples don't get too small)

• Jeff Zimmerman says:

I will hopefully be able to look at this soon. I will need to regress the numbers to the league average.

• Hank says:

The sample size might be tough, but especially for someone like Gardner (and others who try to work the count) it would be interesting to see his swing % with 2 strikes. While one would expect the swing % in the strikezone to obviously change with 2 strikes, it would be interesting to see how much of a change in discipline there is on pitches outside of the zone (essentially subtract the 2 strike swing % plot from the less than 2 strike swing % plot)

In theory you could consider the change within the zone vs the change out of the zone as a different way of measuring plate discipline.

Anyway…. cool stuff!

7. Krog says:

Scrolling through this post makes me feel like I’m playing some trippy 80′s era arcade game.

8. fang2415 says:

Interesting. I’d love to see some of these in conjunction with the metrics discussed by Tango at http://www.insidethebook.com/ee/index.php/site/comments/swing_rates/.

AFAICT, the numbers discussed there look like pretty good ways of measuring who sees the zone best (i.e., players who both swing at lots of strikes and take lots of balls). It’d be interesting to see a visual representation of how those players swing compared to others.

9. Jaik Jarrkjens says:

This is really interesting stuff. I love the colors. Guerrero’s chart is hilarious – flaming red and orange anywhere near the strike zone. And then there’s the almost complete absence of light purple. If the pitcher chucks a ball in the general vicinity of the plate, there is a pretty good chance that Guerrero will swing. I guess we already knew that, but the colors really bring it home for me.

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