Mandatory Credit: Josh D. Weiss-US PRESSWIRE

Jair Jurrjens and PitchFX Part II

Welcome back to my first insights and experiments with PitchFX and Jair Jurrjens. If you didn’t catch the first part of this series you can check that out right here.

In Part I we talked about the use of his pitches from 2010 to 2011 and took a quick glance at his whiff percentage for each pitch during the respective seasons. Today we are going to be looking at the sabermetric outcomes, as well as the speed and movement on his pitches.

Let’s jump right into it then:

the rest after the break…

Sabermetric Outcomes


Pitch Whiff/Swing GB/BIP LD/BIP FB/BIP
FA 19.14% 42.19% 18.75% 32.81%
SI 9.25% 39.78% 19.35% 33.33%
SL 38.69% 39.53% 18.60% 30.23%
CH 24.23% 39.08% 25.29% 28.74%


Pitch Whiff/Swing GB/BIP LD/BIP FB/BIP
FA 18.06% 34.25% 16.44% 40.41%
SI 8.67% 56.38% 13.83% 26.60%
SL 33.95% 30.68% 13.64% 51.14%
CH 13.77% 50.00% 17.11% 28.95%

The only good thing I can pull out of this data is that all of his pitches this year resulted in less line drives, which could be him locating pitches better or simply the luck he accrued in the first half of the season. Other than that nothing else looks good.

All of his pitches dropped off in whiff/swing% especially the change up which is getting us closer to finding out why his K/9 dropped so much. We need to check in on the speed and movement before we can really understand however.


Pitch Horizontal Movement Vertical Movement Speed (MPH)
FA -3.24 -13.72 92.05
SI -7.64 -15.90 91.47
SL 5.25 -32.33 81.20
CH -8.90 -23.99 84.19


Pitch Horizontal Movement Vertical Movement Speed (MPH)
FA -3.42 -14.94 89.81
SI -7.78 -17.30 89.52
SL 4.53 -32.78 79.69
CH -9.24 -22.80 83.99

From 2010 to 2011 Jurrjens lost 2.24 mph on his fastball, 1.95 mph on his sinker, and 1.51 mph on his slider. The changeup on the other hand was pretty much the same (.2 mph slower). All of this is basically your worst case scenario. You don’t wan to lose speed on any of your pitches but the changeup because the speed differential is what makes the pitch effective in the first place (hence the name changeup, as in “change up the speed”).

This is likely the reason the change up became so ineffective this season (13.77 whiff/swing % compared to 2010’s 24.23 whiff/swing %). A fastball more than 2 mph slower, plus the increased use of his slider, where probably the two reasons the changeup didn’t get as many whiffs as 2010. The speed differential in the fastball and the changeup during 2010 was 7.86 mph. In 2011 that differential shortened to 5.82.

The next thing we can talk about is the movement of JJ’s pitches. From 2010 to 2011 there isn’t a huge difference in horizontal movement or vertical movement. So it looks like the biggest impact on Jair Jurrjens has been the lack of velocity, like so many people have been saying. I just took a little while to get there.

This wraps up the mini series on JJ and PitchFX. If you have learned anything from this let me know, I would love to know if I am actually giving you guys some insight. I know I have improved my knowledge of pitching stats based on this little project. If you think I did a bad job, let me know what I can do better or what stats I didn’t use properly.

The UNC-Duke game is coming on so I’ve got to roll. Let’s go Heels! (I really hope they win because this is being published the morning after the game…)

Tags: Atlanta Braves Jair Jurrjens PitchFX

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