Tuesday, August 31, 2010

Matt Kemp's Struggles: Fastballs and Breaking Balls

Kensai over at Memories Of Kevin Malone had a fantastic and exhaustive post on the struggles of Matt Kemp this season. If you haven't read it yet, go read it right now before you continue this post.

A very short Cliff Notes version. Basically, Matt Kemp has been struggling this season, and even if you account for the low BABIP, he is still striking out at a higher rate this season compared to last. What also confounded me that even though he has a higher strikeout rate, he is also setting a career high in walk rate as well. Usually, drawing walks and getting struck out are thought of as tradeoffs, opposite ends of the "patience scale." Kensai also had a meticulous look at the changes in Kemp's swinging mechanics, and he did find a change that hopefully the Dodgers are aware of.

I would like to extend on Kensai's post using PITCHf/x. There are two areas I'd like to investigate: 1) Is Kemp swinging at more strikes in 2010 compared to 2009 and how? and 2) Is Kemp making less contact in 2010 compared to 2009 and how?

To answer these two questions, I'd like to look at Kemp against all fastballs (four-seamers, two-seamers, cutters, and splitters) and against all breaking balls (curveballs, sliders, and changeups). Let's get started with a table of Matt Kemp's plate discipline and swing outcome rates in 2009 vs. that of 2010, broken down between fastballs and breaking balls and by pitcher's handedness:


A lot of numbers in this table. When reading this table, be sure to remind yourself that the blue rows are last year and the white rows are this year. FB stands for fastballs and BB stands for breaking balls. Changes to note between 2009 and 2010: Kemp is swinging less against pitches from RHP but more against pitches from LHP. But in all cases, he is getting more swinging strikes, as well as making less contact, save breaking balls from LHP. This in turn results in less balls in play from Kemp. The last three columns are at a per swing rate (whereas SwStr%, Contact%, and In Play% are per pitch). When Kemp swings, he is whiffing far more in 2009 than in 2010 against BOTH fastballs and breaking balls and RHP and LHP. He is also getting less contact on the ball when he swings in all cases (again, Kemp has performed better in 2010 in In Play% only against breaking balls from lefties).

I have a lot of plots coming up, so I'd like this to be organized and I'll do my best to make concise inferences from the plots. I will be looking at the swinging strike percentages and contact percentages of each combination of fastballs/breaking balls and against righty/lefty. The plots on the left are 2009 and the ones on the right are 2010. There will be four sets of four plots each in the following order:

1) Kemp against RHP fastballs in 2009 vs. 2010 (SwStr% and Contact%)
2) Kemp against LHP fastballs in 2009 vs. 2010 (SwStr% and Contact%)
3) Kemp against RHP breaking balls in 2009 vs. 2010 (SwStr% and Contact%)
4) Kemp against LHP breaking balls in 2009 vs. 2010 (SwStr% and Contact%)

First up is SwStr% and Contact% of Matt Kemp against 1) RHP fastballs:


The red contour lines tell us that Kemp chooses to swing 50% of the time when a ball is thrown within the contour line. This is what I call Kemp's swing zone, so the red circles refer to this. Kemp is swinging at RHP fastballs less in 2010, but is whiffing at a much higher rate as well. He is also making much less contact. The top two graphs show Kemp swinging and missing more, while the bottom two graphs show Kemp making less contact, particularly on high inside fastballs.

Second is SwStr% and Contact% of Kemp against 2) LHP fastballs:


Here in his swinging strike plots, Kemp has actually started to swing more on LHP fastballs down and out of the zone, so his swinging strike rate there is up. But he is also missing a lot more LHP fastballs this year that come down the middle over the plate, ideal pitches for the right-hander to hit out of the park. Looking at his contact plots, we see similar colors in where he makes the most contact, but we see a huge shift. Last year, Kemp made contact off a lot of LHP fastballs down the middle of the plate, but this year, the epicenter of that contact hotspot has shifted a full foot up from the direct middle of the zone to the top of the zone. We can infer that Kemp is making less contact off the sweet spot of his bat, and making more high fastball contact that usually result in pop outs.

What about breaking balls? Third is Kemp's SwStr% and Contact% against 3) RHP breaking balls:


The SwStr% plots don't seem to change much for RHP breaking balls. Kemp is swinging more, however, on inside RHP breaking balls than before. He is clearly making less contact off RHP breaking balls this season compared to last. Last year, it also looks like Kemp made more contact off RHP breaking balls coming to the heart of the plate.

Finally, let's look at the fourth and final set of plots of Kemp's SwStr% and Contact% against 4) LHP breaking balls:


These show Kemp swinging at LHP breaking balls in the strikezone in 2009, but low and inside out of the zone in 2010 in his swing zones. As a result of chasing inside breaking balls, Kemp's SwStr% in 2010 in that lower inside corner has increased dramatically. This also shows in his Contact% plots, as the center of his contact hotspot has also shifted from the very middle of the zone toward the lower inside corner of the zone.

There's a lot of information in the previous 16(!) plots, but here are the Cliff Notes version of what I found about Matt Kemp this season compared to last season:

1) Swinging at less pitches (more walks), but whiffing more on hittable pitches (more K's)
2) Making less contact, but when he does make contact, he also puts the ball in play less
3) Swinging at (and missing) more high fastballs from RHP, resulting in less contact
4) Whiffing on LHP fastballs down the middle of the plate, making more contact on high LHP fastballs and less on down the middle LHP fastballs
5) Swinging at more inside RHP breaking balls and making less contact down the middle
6) Chasing low inside LHP breaking balls more, whiffing a LOT more, and making less contact down the middle

In general, what I present here is what we already know: Kemp is swinging and missing a lot more. But I hope that I was able to demonstrate clearly that Kemp is struggling against both fastballs and breaking balls, and I have shown where he is whiffing on them and where he is making less contact. Whereas Kensai looked at the "why," I'd like to say that I've taken an indepth look at the "how."

There could be plenty of reasons why Matt Kemp's whiffing behavior is so widespread, and this bolsters my belief that Kensai at Memories Of Kevin Malone is on to something with his post on the difference in Kemp's swinging mechanics. It's possible that Kemp started chasing inside sliders, high fastballs, and missing vulnerable pitches that he used to crush for independent reasons all at the same time, but I'm inclined to believe that a difference in mechanics (read Don Mattingly: and approach) is more likely to cause all of this simultaneously. And perhaps there is such a thing as being "too patient."

To evaluate if Kemp has changed his approach, I'd like to look at how Kemp's swinging behavior and outcomes have changed from last year based on count situation. Next time, I'll take a look at Kemp's tendencies and results on the first pitch, when the opposing pitcher is behind in the count (more balls), and when he's ahead in the count (more strikes).

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