August 17, 2011; Atlanta, GA, USA; Atlanta Braves starting pitcher Jair Jurrjens (49) pitches in the first inning of the game against the San Francisco Giants at Turner Field. The Giants beat the Braves 7-5. Mandatory Credit: Daniel Shirey-US PRESSWIRE

Jair Jurrjens and PitchFX Part I

I stumbled across Brooks Baseball today and have found the best place to analyze pitchers to the fullest. They have so much stuff on the site that right now I can’t really keep up. Hopefully that will change with the more time I spend there and eventually I might be able to give you guys some in depth pitching break downs. You know, the stuff that Ben Duronio does all the time.

But for now you will have to settle for my rookie level knowledge of pitchFX and the stats they use. Things like vertical and horizontal movement, and analyzing graphs that deal with pitch movement, speed, trajectories, and pitch locations.

If any of you who are reading this have a good knowledge of pitchFX please let me know of any mistakes I may have made, and give me some beginner tips if you feel like I need them. With that said let’s jump into it with our most controversial pitcher: Jair Jurrjens.

jumping into PitchFX with JJ after the break…

To start we should look Jurrjens pitch types and the frequency in which he uses them.

all of the stats and graphs you will see from here on out can be found at Brooks Baseball here.

Pitch Count Frequency
Four-Seam FB (FA) 697 39%
Sinker (SI) 428 24%
Slider (SL) 284 16%
Changeup (CH) 373 21%

This graph shows his pitches and frequencies for 2010. When we look at just 2011 you will see some pretty big differences:

Pitch Count Frequency
Four-Seam FB (FA) 913 40%
Sinker (SI) 392 17%
Slider (SL) 446 20%
Changeup (CH) 525 23%

You can see that used the sinker a whole let less than he used to and began to throw the slider and fastball more, probably to try and get more strikeouts. At the beginning of last year we hear a lot of talk about Jurrjens changing his approach and the numbers confirm that.

But how effective is his slider? I am going to try and find out with this ingenious new PitchFX data I have stumbled upon.

We are going to be comparing his 2010 data (a lot of sinkers) with his 2011 data (less sinkers, more sliders). We are going to use Pitch Outcomes and after that we will use Sabermetric outcomes to see if the 2011 approach is worth using in 2012.

Pitch Outcomes


Pitch Frequency Ball Whiffs
Four-Seam Fastball (FA) 39% 31.24% 8.90%
Sinker (SI) 24% 38.21% 3.77%
Slider (SL) 16% 36.62% 18.66%
Changeup (CH) 21% 36.19% 12.60%


Pitch Frequency Ball Whiffs
Four-Seam Fastball (FA) 40% 35.60% 7.34%
Sinker (SI) 17% 31.89% 3.83%
Slider (SL 20% 37.44% 16.37%
Changeup (CH) 23% 33.33% 7.24%

Right away you might think that it’s better to throw the slider than the sinker because of the huge whiff rate difference, but the pitches aren’t used for the same thing. Unless you have a disgusting sinker you probably aren’t looking to miss a bat you are trying to induce a groundball. We will get into that more in a minute.

What we can find out however is that all of Jurrjens pitches produced a significantly lower whiff rate when he relied on the slider more than the sinker. It makes sense that the slider itself would be a bit lower but all of the change up and fastball? In 2010 Jurrjens’ change had a 12.60% whiff rate and it dropped all the way down to 7.24% in 2011. Since he was throwing the slider at a much higher rate the batters probably adjusted and sat back longer, which helped to wait on the change as well.

The increased use in the slider could still be better for Jurrjens if the K rate in 2011 is significantly better than 2010.

  • 2010 K/9- 6.65
  • 2011 K/9- 5.33

Looks like the slider actually didn’t help Jair with much of anything. The drop in his K rate is also due to the fact that Jurrjens fastball velocity dropped from 91.3 to 89.1. Let’s hope that he can bump that back up in 2012 and blame ‘11 on the knee.


I am going to go over the Sabermetric Outcomes in Part II of this PitchFX intro and also talk a bit more about the velocity of Jurrjens pitches as well as the movement. Let me know what you think about PitchFX and my use of it. Good, bad, awful? I will be doing a lot more research with this tool in the coming weeks.

Tags: Atlanta Braves Jair Jurrjens PitchFX

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