Kenley Jansen’s Other Pitch

Kenley Jansen is one of the best relievers in baseball. This season, in some ways, he has been better than ever, posting a career low xFIP and career high swinging strike rate. The rest of his peripherals are in line with his career averages. His ERA isn’t great, but you should never look at reliever ERAs. He’s tenth among relievers in strikeout rate, and eighth in K%-BB%. Most of you already know this.

One thing to note, though, is how Jansen’s pitching has evolved over the course of the season. Here is a breakdown of his pitch usage month-to-month throughout his career.

KenleyPitchUsage

So far in July, Jansen is throwing his highest percentage of not-cutters in his career. He’s still throwing them 80% of the time, but about 16% of his pitches this month have been sliders. That high rate of slider usage is his highest since the middle of 2011. Some of that is small sample size, since Jansen has pitched just seven innings this month (remember when we were worried about his high workload?). However, even when looking at full season pitch usage, he’s throwing more sliders than he has in three years.

It’s still a small number, but it’s worth looking into. What is the “one pitch pitcher’s” other pitch? First of all, it’s fun when it’s working well:


GIF Link

That pitch was against Dan Uggla, so it only partially counts, but the pitch has been great when he has used it. You can see pretty clearly what Jansen is trying to do with the pitch in this plot, courtesy of Baseball Savant:

KenleySliderPlot

Of the 45 sliders Jansen has thrown in 2014, only four have been in the upper 2/3 of the strike zone (five have missed off the plate and up as well). 36 of the pitches have either been in the lower 1/3 of the strike zone, low, or off the plate below the midpoint of the zone. Jansen’s average slider location is at its lowest position of his career. He’s throwing it with more sink (downward vertical break) than ever. Currently, Jansen’s slider averages about 2 inches of sink (compared to 9.5 inches upward movement for the cutter). 180 relievers have thrown at least 40 sliders this season; Jansen’s slider has the 13th highest sink among all of them.

The extra sink and lower location are working. Jansen is getting good results on the pitch. Ignoring the 11 sliders he threw in 2009, he has a career high whiff/swing rate on his slider, 45.16%. In each of the last three seasons, Jansen’s slider has had a higher whiff rate than his cutter (as has his two seamer, which is a topic for another post). Jansen’s slider whiff/swing rate is 35th among the same reliever group mentioned previously.

As a result, Jansen is getting a relatively disproportionate number of strikeouts on the pitch. Twelve of his 66 strikeouts have come on the pitch, the 18.2% rate much higher than the 6.8% overall pitch usage. 28 of Jansen’s sliders have been thrown with two strikes, and another 11 have come on 0-1 counts. He has only thrown the pitch three times while the batter is ahead in the count (curiously, two of those pitches were to Carlos Quentin, in separate sequences). It’s his secret out pitch.

To get a better picture of  what the above numbers mean, here an outcome breakdown of the 45 sliders thrown this season:

  • 11 balls
  • 3 called strikes
  • 10 fouls
  • 14 whiffs
  • 7 balls in play – 3 ground balls, 2 fly balls, 2 line drives – 2 hits, both singles, 5 outs

That’s really, really good. On a rate basis, Fangraphs grades Jansen’s slider as his best pitch this year. On a cumulative basis it’s still the cutter, of course. It’s hard to tell if the positive results are because he throws the other pitches so often. It’s hard to study, since Jansen is so unique. The high degree of sink might point away from the frequency and towards it just being a really good pitch on its own. If Jansen continues his current pattern of throwing the slider more, I suppose we’ll find out.

These numbers and figures were generated before Tuesday’s game, where Kenley Jansen threw two sliders in nineteen pitches (10.5%). One slider resulted in a whiff, one was left up and hit for a line drive single. It was the fifth slider in the upper 2/3 of the strike zone, but the damage was still limited.


About

Daniel Brim grew up in the Los Angeles area and remains a Dodger fan despite currently residing in Salem, MA. As an engineer, he’s fascinated by the math and science behind the game of baseball, which probably explains a lot. He started “Blog To The Score” in late 2013 to dig deeper into the numbers behind the Dodgers. In its brief lifespan, it gained attention from local and national media. You can find him spending too much time in the comments section or on Twitter.


809 comments
Disgruntled Goat
Disgruntled Goat moderator

so who's the mystery okay-ish starter than we'll end up getting? this year's nolasco? 

Birdman79
Birdman79

Alright kids.....Bird is checking out of work. The food truck is up at the winery.....

Gregory Polanco
Gregory Polanco

Charlie Morton's strand rate only thing higher than Tim Lincecum during the off season

 Kyle
Kyle

Pirates WHIP is off the charts this game.

Birdman79
Birdman79

Hey Charlie Morton....your nickname is GROUND Chuck......GROUND....as in GROUNDERS.

 Kyle
Kyle

Schwerty za toobie minga!

 Kyle
Kyle

(pittsburgher speak)

Seager_for_Senate
Seager_for_Senate

@DBrim Or time and molecular could suddenly  freeze, suspending us all in a trade or no-trade limbo forever. And then what, Connolly? Then what?

M-P
M-P moderator

@Jobu yeah, we don't know any of that is true, though.

Hoze
Hoze

@Jobu I think you mean Marmol, rather than Perez

Hoze
Hoze

@Professor Towel @Hoze @Jobu I didnt mean to downplay his performance, because he was in some ways useful (mediocre) but picked a player with little promise acquired at the deadline. 

very smart towel
very smart towel

@Hoze @Professor Towel @Jobu yeah but half of that deal was getting rid of Guerrier.


Ned could trade Perez for a slightly less shitty but more expensive reliever and I'd be fine with it.