Potential Starting Pitcher K% Decliners

Yesterday, I took a look at the potential pitcher strikeout percentage surgers based on the regression equation I developed and shared with all of you last week. Today, I will look at the opposite side of the coin — those pitchers whose expected strikeout percentages are significantly lower than their actual strikeout percentages.

  L/Str S/Str F/Str K% xK% Diff
Yu Darvish 27% 25% 25% 34.8% 30.4% 4.4%
Felix Hernandez 26% 19% 27% 26.6% 22.3% 4.3%
Tyler Lyons 30% 10% 25% 15.8% 11.8% 4.0%
Jerome Williams 23% 16% 27% 18.2% 14.5% 3.7%
A.J. Burnett 31% 17% 27% 28.7% 25.2% 3.5%
Jordan Zimmermann 25% 13% 27% 15.8% 12.4% 3.4%
Adam Wainwright 29% 17% 25% 24.4% 21.0% 3.4%
Edwin Jackson 23% 17% 28% 20.1% 16.9% 3.2%
Max Scherzer 29% 20% 28% 31.4% 28.2% 3.2%
Eric Stults 29% 11% 28% 18.1% 15.0% 3.1%
Unweighted Population Avg 28% 15% 27% 19.1% 18.9%  

Before we complain that this formula doesn’t work because Yu Darvish is atop the list, let’s just marvel at that S/Str rate. That leads all of baseball among starting pitchers…and easily too. Next highest is Jeff Samardzija and Anibal Sanchez at just 22%. Anywho, a pitcher is unlikely to post a K% this high without some luck. Sure, his stuff is ridic, but his current mark ranks second among all qualified starting pitchers since 2000! Of course, even an expected regression won’t change the fact that he’s likely still a top five starter (perhaps better? top three? top one?) the rest of the way.

Felix Hernandez ranks second because of his lack of called strikes and just league average rate of foul strikes. Still, I am amazed at how dominant he has remained despite his fastball velocity nearly declining in a straight line since 2007. Even though his velocity is at the lowest of his career, his SwStk% is currently at its highest. His xK% is right around what he’s posted since 2009, so it isn’t too hard to believe.

Woah. Tyler Lyons hasn’t exactly been a strikeout machine since making his debut, and yet xK% suggests that he should be even worse! That’s not a good sign and suggests that he’ll struggle to even earn NL-Only league value. More likely, he’ll lose his rotation spot in short order and return to the minors.

It’s hard to figure out what A.J. Burnett is doing differently that has led to the huge strikeout percentage spike. His pitch mix is the same as it has always been and his velocity is nearly identical to last season. xK% suggests some of that jump has been a result of good fortune, but even his expected mark is well above years past. It’s truly hard to believe the 36-year-old could remain this dominant all year.

Wow, Jordan Zimmermann! That’s what happens when you induced a below league average rate of both looking and swinging strikes. Pretty shocking given his outwardly good stuff and strong fastball velocity. I wondered if maybe Zimmermann has consistently underperformed his xK% and this has not been the case. In every previous season, he has actually slightly outperformed. While I have to imagine both his xK% and K% will rebound, his ERA/SIERA differential makes him a strong sell high candidate in my view.

Could you believe if Edwin Jackson‘s strikeout percentage plummeted to the level xK% is hinting at? Though he barely has any redeeming qualities at the moment, at least he has contributed positive value in strikeouts for those fantasy owners still brave enough to keep him active. But what if those strikeouts disappeared? Oh boy, Chicago, we have a problem. If he didn’t appear here, I would have suggested that he makes for an interesting buy low candidate for those owners who like to embrace risk given his 3.86 SIERA. But maybe he’ll just be worthless in all leagues all season long.

Here are all of the pitchers whose xK% is lower than his K%.




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Mike Podhorzer produces player projections using his own forecasting system and is the author of the eBook Projecting X: How to Forecast Baseball Player Performance, which teaches you how to project players yourself. His projections helped him win the inaugural 2013 Tout Wars mixed draft league. He also sells beautiful photos through his online gallery, Pod's Pics. Follow Mike on Twitter @MikePodhorzer and contact him via email.


18 Responses to “Potential Starting Pitcher K% Decliners”

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  1. JLuman says:

    I like this idea. I suspect there is an artificial bias introduced in your process. I think this bias should be “easy” to fix. Have you noticed that your potential surgers are mostly bad pitchers and your potential decliners are mostly bad pitchers?
    You’re correlating a rate from fractions of a whole. Therefore your inputs are not independent of one another. For example, if the next pitch thrown is a strike looking the rate of strike swinging correspondingly declines. You can get independence by correlating counting stats against one another and then transforming back into rate stats. Correlate total strikeouts against strikes looking/swinging/fowling, normalize with strike type per batter faced.

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  2. ndbrian says:

    I wonder if Burnett’s increased performance relative to expectation is due to Rusell Martin’s receiving ability. I’m admittedly not good enough at this yet to do the analysis, but it seems like A.J. gets a lot more strikes looking (last night aside) than he has in the past, and more than most. Being able to gain some strikes that way, would, in theory, give him better counts to throw his other pitches.

    Anybody better at this than I am agree or disagree?

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    • Fedee_ says:

      I don’t know if “framing” pitches actually works but I’ve heard it on tv so I guess at least a part of it has to be true. I remember AJ in his Jays days spoke highly of Bengie Molina exactly because he held the baseball for an extra second which gave the umpire the chance to punch out the hitter.

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      • Clifford says:

        “framing” pitches actually works. as a catcher if you are constantly stabbing at the ball or guessing its final location, it just makes the pitches look bad…conversely, if a catcher has soft hands and always has their glove positioned correctly, it gives off the perception that he’s hitting his spots.

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      • Burnett has indeed gotten more looking strikes this year, tied for the highest rate of his career. That’s actually the only strike type rate above his career average. Whether that’s due to Russell Martin or not, we have no idea, but that’s what’s behind his K% surge.

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      • Name says:

        Does Martin call the game? If so, a change in sequencing might be the cause of AJ’s K%.

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  3. Rob says:

    Really? Zimmermann a sell high?

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  4. rotowizard says:

    When it comes to AJ Burnett, I have two words and a phrase. Russell. Martin. Pitch Framing.

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  5. KTrout says:

    Hey Pod, just when I was searching for some kind of confirmation that I should trust EJax for just a little bit longer…all I wanted was a 4.00, half dozen wins, and 150 K’s, was that too much to ask?

    In a deep NL-only, I’m pretty much stuck with him right? Pick one: Daniel Hudson, Tom Koehler, Edwin Jackson, an empty bench spot, Brien Taylor, or a box of “clean dirt”.

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    • Haha, yeah, I hear your frustration. Brien Taylor, that’s great. I think you gotta stick with Jackson and pray

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      • KTrout says:

        How exactly is it that his FIP is 3.55, and his ERA is literally twice that after 11 starts? Does the outfield just walk off the field when he takes the mount?

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      • Literally just laughed out loud. His LOB% is putrid, which I could only imagine is some terrible luck. He’s never experienced this before. Remain excruciatingly patient.

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  6. Todd Borland says:

    Whom would you target to sell Zimmermann? Another starting pitcher for example?

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    • When I try selling high, I go all out. Worse come to worst, it gets rejected and you shoot a little lower. So why not try for Hamels and Cain first and work down from there? Maybe even Sabathia though his last start makes it more difficult.

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      • Todd Borland says:

        So you think Hamels turns it around? How many games do you think he ends up winning?

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      • Yeah, I think Hamels will be fine. I have no idea about the wins, that’s impossible to project. And speaking of Zimmermann, just read that he was traded in a Razzball Commenter League for Chris Davis. So clearly he has serious sell high potential. In fact, might even be worth offering Zimm for Hamels AND another upgrade.

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  7. KTrout says:

    So I’m still staring at Edwin Jackson’s numbers…from 2009, his change up has gone from 13.5%, 8.6%, 8.1%, to 1.4% this year. Once your fastball is sitting at 90mph, I suppose an 87mph change-up isn’t all that useful anymore?

    Does xFIP give a damn that your arm is just really tired?

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