Pitch Receiving and Pitch Types

I think I’m the guy at FanGraphs who’s most interested in the field of pitch-framing research, so, hey there, here comes another post about pitch-framing. The idea of the importance of receiving a pitch correctly has been around forever, but only more recently have people begun to feel like they can measure who’s good and who’s bad at it. You know the good ones are represented by Jose Molina, and you know the bad ones are represented by Ryan Doumit. There are calculations that use PITCHf/x data to figure out strikes above or below average, for catchers.

What isn’t quite so clear, yet, is how we should interpret those numbers. Catchers aren’t all catching the same pitchers in the same ballparks in the same counts with the same umpires and the same opposing batters. It’s complicated, because of course it’s complicated, and I’m interested in the idea of some guys being harder to catch than others. Some guys will be more and less easy to frame. At its core, this is because some pitches should be more and less easy to frame. Catching a 95 mile-per-hour fastball is going to be different from catching a 70 mile-per-hour lollipop curve.

Following is some initial research into what we can think of as strike zones by pitch. PITCHf/x already provides pitch classification, and while the classification is imperfect, it’s gotten better and it’s close enough over big samples. We can tally up how many of each pitch type there were, and we can tally up how many of those pitches went for strikes. We can also tally up how many of those pitches were in the strike zone, and how many of those pitches resulted in one-of-zone swings. From here, we can end up with a number of expected strikes, which we can then compare to the number of actual strikes.

That’s what you’re going to find in the table below. With help from my friend and co-writer Matthew Carruth, I identified all pitch types thrown at least 1,000 times in 2012. The column “Diff/1000″ refers to actual strikes minus expected strikes, per 1,000 called pitches. A positive number means there were more strikes than expected, while a negative number means there were fewer strikes than expected. The overall average here is pretty much exactly 0. More strikes than expected implies easier pitch receiving; fewer strikes than expected implies just the opposite. The data:

Pitch Count Diff/1000
Sinker 64205 6
Two-Seam 91011 5
Four-Seam 238423 5
Cutter 39013 4
Splitter 9283 0
Changeup 71125 0
Slider 109157 -6
Fastball 1514 -10
Curveball 69790 -13
Knuckleball 2799 -26
Knuckle Curve 1114 -49

A few things to explain, first. The knuckleballs are all R.A. Dickey knuckleballs, so it’s not like we’re drawing from a big, averaged-out sample. That’s biased by the particular pitcher and the particular catchers. The knuckle curves are mostly A.J. Burnett knuckle curves, so again, we’re biased by the pitcher and the catchers. That generic “fastball” listing isn’t grouped with the other fastballs, and we’re probably seeing small-sample noise, there. A sample of 1,514 pitches is a small sample, for these purposes.

The results are probably about what you’d expect. Fastballs are the easiest pitches to receive, getting the more favorable strike zones. There’s little difference between the sinkers, the two-seamers, the four-seamers, and the cutters. As pitches move more, we see less favorable strike zones. Of course it’s challenging to catch a knuckleball — nobody knows what the pitch is going to do. Of course it’s challenging to catch a big curveball, and maybe especially an A.J. Burnett curveball. Catching those pitches might require more movement on the catcher’s part, and of course the break can be deceiving. Pitches with more movement will be more difficult to locate, too, and there’s presumably a strike-zone benefit to pitching around your spots instead of unpredictably all over the zone.

What isn’t controlled for in here are the counts. Breaking balls are thrown in a lot of pitcher-friendly counts, and pitcher-friendly counts have tighter strike zones. The opposite is true for fastballs. That’s going to be a factor, although it’s unlikely it negates all the differences we observe.

A guy who throws a lot of sinkers is Brad Ziegler. Over the last few years, Ziegler has had one of the most favorable strike zones in baseball. There could be a relationship there, and here’s a .gif example of Ziegler getting a borderline call:

Meanwhile, here’s a .gif example of A.J. Burnett not getting a borderline call on a knuckle curve:

On their own, the two .gifs don’t prove anything, but people always like looking at images instead of text. The surprises in here are few and far between. It seems like it’s the easiest for catchers to receive fastballs. It seems like it’s the hardest for catchers to receive breaking balls. There’s more work to be done, here, more steps we can take to get better ideas of what’s going on. How about fastballs that move in different ways? That’ll be a post for another day, probably. Same with fast curves and slow curves, probably. Lots of potential divisions, and who doesn’t like dividing?

There’s a lot that goes into determining what kind of strike zone a pitcher will have. Each and every one of those factors is absolutely fascinating.




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Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.


21 Responses to “Pitch Receiving and Pitch Types”

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  1. channelclemente says:

    I think Burnett actually throws a ‘spike’ curve, but same difference. A question, guys like Molina, Posey, and a few others stop and ‘read’ the balance of the hitter, before they set the target. Is it possible to quantify that attribute in any more or less direct way.

    I’m sure this passed under your microscope… http://www.baseballprospectus.com/article.php?articleid=15093#95868

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    • J says:

      I thought spike curve and knuckle curve are exactly the same thing. You did say “same difference”, but then I’m not sure why you brought it up.

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      • channelclemente says:

        The grip is different, and I’m not inclined to call a spade and club. The guy who throws the spike curve has been known to file his nails and doctor the ball to his advantage in plain site…Burnett.

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      • AK7007 says:

        Wikipedia does it best: “The first, more common pitch called the knuckle curve is really a standard curveball, thrown with one or more of the index or mean fingers bent.” – Which is what Burnett throws.

        People also call this version a spike curve, because the “knuckle curve” that comes to most people’s mind is probably this: “The second type of knuckle curve is a breaking ball that is thrown with a grip similar to the knuckleball. Unlike a knuckleball, which spins very little, a knuckle curve spins like a normal curveball because the pitcher’s index and middle fingers push the top of the ball into a downward curve at the moment of release.”

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  2. Steve says:

    Hello Jeffy Boy. :-)

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  3. Travis L says:

    It would also be interested to explore pitchers’ additional strikes and pitch height. Pitches in the dirt are obviously more difficult to receive than high pitches. Instead of looking at strike/ball differences, it would be neat to identify the pitchers with the highest rate of pitches in the dirt and correlate that to their extra strike percentage.

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  4. This has been a really insightful series, thanks for all the hard work Jeff.

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  5. Hank says:

    I like looking at the impact of pitch type – I’m not sure Mike Fast’s work in this area controls for pitch type. I’m assuming sample size starts becoming an issue if you have to control for pitcher and pitch type. Does anyone know for sure one way of the other whether Fast’s work controls for pitch type?

    One other area that might be worth looking at is handedness (both pitcher and hitter). A catcher receiving a loaded lefty or righty rotation may also impact the framing #’s

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  6. Robert J. Baumann says:

    Based on the provided gifs, I wonder if where the pitch breaks in relation to where it crosses the plate might not make a difference.

    Since Burnett’s pitch has a much slower, loopy break, it could be that the pitch crosses the front plane of the plate “outside” of the strike zone but then sort of breaks back into what appears to be the zone (or bordering on the zone) when it is framed. The Zeigler pitch seems to break much later in relation to where it crosses the from of the plate.

    I’m no expert, clearly. Just spinnin’…

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  7. Baseball fan says:

    I think all the changes now look great!

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  8. StrikeThree says:

    If both pitches had been framed by receivng wrist supinated (palm up), I think they’re strikes. Catch “am I Being Framed” at BTB.

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  9. I Agree Guy says:

    Is commenting still broken?

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  10. dave says:

    no such thing as a knuckle-curve…..might be a knuckler that you can make break one way when you want……. a curve ball needs spin in order to curve….a knuckleball isn’t supposed to spin

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    • Nem says:

      A knuckle curve isn’t called that because it has the knuckleball’s trademark lack of spin. It’s name comes from the fact that you hold the ball with a modified knuckleball grip. And from there you impart the traditional curveball rotation.

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  11. Jeff says:

    Great work on this Jeff! I’m inclined to believe that umpire discretion and missed calls are a huge factor in this study. Probably magnified more so at the ML level because of the high quality of catching play versus that of the minors or college/prep ball. Thoughts?

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  12. Synovia says:

    “What isn’t controlled for in here are the counts.”

    This whole article seems like a big miss than, as just last week we had an article showing how different the strike zone is in a particular count. It seems a big strange to ignore this.

    Also, pitch framing is one of the things I’d love to see dissapear. How well a player fools the umpire into making an incorrect call isn’t all that interesting to me. Doesn’t seem very different than hiding the ball, or anything like that.

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