Command PostApril 26, 2007
That Sinking Feeling
By Joe P. Sheehan

This week I wanted to look more in-depth at the aerodynamic fingerprints of different pitches, particularly sinkers. A sinker is a two-seam fastball that drops as it approaches the batter and is frequently pounded into the ground by a hitter. Pitchers who throw good sinkers tend to rely heavily on the pitch and don't need to worry as much as a "normal" pitcher about changing speeds.

The whole point of changing speeds and throwing different pitches is to induce weak contact (or strike-outs), but when a sinker is thrown properly, a batter generally makes poor contact and hits it on the ground anyway. Armed with detailed information about each pitch, I looked at three sinkerballers and made some interesting observations about each of them.

Derek Lowe was the first pitcher I studied. Here's a graph showing the breaks of Lowe's three pitches, a sinker, slider and curveball over parts of two starts this season, on 4/13 and 4/24. Lowe pitched well in both these outings, allowing four runs over 16 innings of work.

Lowe all.png

One thing that immediately jumps out to me in the chart is the consistent horizontal break, compared to a non-spinning pitch, of his sinker. Most breaks that I have seen, both horizontal and vertical, have been much more spread out, similar to how the vertical break of his sinker appears. As I mentioned in my previous article with regard to release point, I'm not sure whether consistency is necessarily a good thing for pitchers. While having a consistent break on a pitch would seem to help the catcher receive the ball and give the pitcher confidence that he knows where he's throwing to, it would also help a hitter who could prepare for only one type of break on the sinker. If Lowe is always this consistent though, it hasn't really been a problem for him.

Another thing to notice on this chart is Lowe's curveball. He throws the pitch infrequently, but both the horizontal and vertical break (compared to a pitch with no spin) are around zero inches. According to the data his curve ends up almost exactly where a pitch with no spin would, and with a speed of 82 MPH, appears to be a meat-ball. Fortunately for Lowe, this isn't the case. The pitch has some movement, measured by the length of the break (defined as the measurement of the greatest distance between the trajectory of the pitch at any point between the release point and the front of home plate, and the straight line path from the release point and the front of home plate) which is 11.5 inches, the greatest of any of his pitches. The hump in Lowe's curveball creates enough deception to allow him to throw it on occasion without getting burned.

Colorado's Aaron Cook is another sinkerball artist. While I had 200 pitches over two starts for Lowe, I only had 103 pitches from Cook, all of them from his start on 4/8. This was a fantastic start for Cook, despite a no decision, as he pitched 9 innings and allowed only one run. Here's a chart showing the break on his pitches in that start.

cook.png Lowe 4.13.png

Comparing the horizontal break on Cook's sinker to Lowe's reinforces how consistent Lowe was. The chart on the right shows Lowe's start on April 13, and even though Lowe had a more consistent break (a tighter bunching of clusters) for all of his pitches compared to Cook, the horizontal break of the sinker was especially consistent. Cook's curve has a break pattern that is typical of a curveball, with the pitch ending up lower than would be expected with a non-spinning pitch. Compared with Lowe's curve, the vertical break is on the left of the horizontal break in the chart, which I believe is a graphic indicator of a curveball. Despite these differences in the way their sinkers moved, Lowe and Cook both had excellent starts in the games I examined, so there are clearly multiple ways to skin a cat here.

I wanted to look at another NL West sinkerball, Brandon Webb, but Gameday has only tracked 83 pitches for Webb so far this season, leading to a much murkier chart than Lowe's or Cook's. There are three basic clusters of pitches, but there is also a collection of scattered points, which I'm unsure how to identify. Even the clusters I'm able to identify are much further apart than most pitchers I've examined. I have noticed some obvious inconsistencies in the data so far, mostly involving the speed and release point, so this break information could be wrong too. The pitches I was unable to identify could be another pitch that Webb throws, but I'd like to see another start worth of information from Webb before I form an opinion on his pitches or their movement.


Excluding Webb, the only other true sinkerball I had a reasonable amount of data for was Carlos Silva. I have information on 110 pitches that Silva threw over two different starts, 4/07 and 4/18, and when I created his chart, I found he has only thrown two pitches, a sinker and change up. Because of the inconsistent way Gameday collected data from those two starts, Silva could have thrown other pitches that weren't collected by Gameday. However, I think if he did have another pitch, he would have thrown it more than a couple of times over 110 random pitches.


The table below shows some interesting information about the three sinkers examined. The numbers measuring the pitches are all median values as opposed to mean values. Silva relies on his sinker more than Cook or Lowe, but his sinker has less of a downward break, measured by both the vertical break compared to a non-spinning ball and the length of the break, which is the number I used to describe the hump in Lowe's curveball. Silva's average sinker ended roughly nine inches higher than a non-spinning pitch would have, while Lowe's and Cook's pitches ended roughly four inches above the imaginary terminus. The backspin on a pitch is what causes it to end up higher than a non-spinning pitch would, so Silva's sinker must have more backspin than Lowe's or Cook's. When a hitter hits a sinker with too much backspin, he still hits a grounder, but as Dan Quisenberry famously put it, "in this case, the first bounce is 360 feet away."

An average sinker from Silva reached its high point roughly seven inches above an imaginary line from release point to home plate, compared to roughly nine inches for Lowe and Cook, leading to a smaller vertical drop for Silva. These observations seem to jive pretty well with reality, as Lowe and Cook are both thought to have better sinkers than Silva, and one thing that could lead to a more effective sinker is getting more downward movement on the pitch.

Name   Sinker%   Speed    Horizontal Break   Vertical Break    Break Length
Lowe   65%       90 MPH   -10.75"            3.68"             9.00"
Cook   68%       93 MPH   -10.02"            4.60"             8.30"
Silva  77%       93 MPH   -10.74"            9.39"             6.85"

For the sake of comparison, and to make sure I wasn't drawing conclusions about a trend that didn't exist, I wanted to get the average values for several four-seam fastballs and see how they compare to these sinkers. For this, I used Matt Morris and Jake Peavy. The table below shows the same information as above, but for Morris' and Peavy's fastballs.

Name     Fastballs  Speed    Horizontal Break   Vertical Break    Break Length
Morris   79         89 MPH   -9.01"             9.47"             6.70"
Peavy    104        95 MPH   -10.32"            8.49"             6.60"

With all the usual warnings about a small sample size, the sinkers appear to be different from the four-seam fastballs, which is a great finding. The fastballs have different horizontal and vertical breaks and a much smaller break length relative to the sinkers. One interesting thing was the similarity of Silva's sinker to the four-seam fastballs. Silva struggled in spring training this year with controlling his sinker and maintaining the sink on the pitch, so perhaps this is numerical evidence of those struggles. Either that, or that's just how Silva's sinker typically behaves, and his normal sinker is different that Lowe's or Cook's.

I was very pleased to discover that pitches were able to be identified using just the horizontal and vertical break values from Gameday. In the future, I'd like to continue looking at different pitches and see the differences between say, Barry Zito and Rich Hill's curveballs, or Johan Santana and Cole Hamels' change up. The fact that there was a distinct difference between a four-seam fastball and a two-seam fastball gives me hope that sifting through the database to find the different types of pitches a pitcher throws is an attainable goal.


It would be interesting to see Silva's patterns in 2005, when he gave up just 9 walks in 187 IP. I believe he was also in the AL top 10 in ERA. The sinker didn't sink last year when Silva went 11-15 with a 5.94 ERA.

With the perpetual pitching shortage, I often wonder why teams don't take marginal velocity/good control minor leaguers and see how they do with the sinker. It worked for Cy Young winner Randy Jones, who usually threw around 75 MPH.

Is Yankee Stadium set up to capture this type of information? I'd love to see a breakdown like this for Wang.

Very, very, very cool (can't emphasize the very's enough).

I finally figured out how (and from where) to load the gameday data into excel. the First things I looked at was Felix Herndandez's first start compared to Jarrod Washburn's first start. A couple things stood out at me, beyond just average velocity and break length. The difference in break on the fastball was signifigant, and of course so was the speed. The "break_length" field was not that different for their fastballs (which was surprising), but Felix had a greater average pfx_x and a lower pfx_z. I thought PFX was the break, but they also have a "break length" field, and break y. I'd assume pfx_x is horizontal break, and pfx_z is where it starts to break (I'm actually not sure on this). If that's the case, Felix's fastballs break more, in a shorter ammount of time (this is obvious visually). The differential in start and end speed of their fastballs was different, Washburn had a difference of ~8.4 mph (I think, dont have the data handy at work), and Felix ~10 mph. This may be normal for hard throwers, I'm not sure, nor do I know what that means, but found it fascinating. FWIW, Cla Merideth had some nasty nasty wicked break on his pitches (average break_length ~13), at least for one appearance I looked at.

The sinker thing was something I was curious about (relative to a predominately 4-seam pitcher), so this was a cool article (not that ll of your gameday XML articles haven't been) to find today :)

I'd LOVE to see the data a couple/few Wakefield starts. Another application that I'd love to see /wrt Gameday data is someone to do pitch reconstructions using the data, to visually see the differences in speed and movement, in a way that models the actually path of the pitches.

Chris Miller,

a few of the gameday parks already do this, showing the arc/location of the pitch. It is slowly being rolled out to all parks (I'm supposed to be doing it in Milwaukee) but the usual contractual issues are holding up the full operation of this app.


For your first point, the fields that are listed in the XML are a bit confusing. Pfx_x is the horizontal break (the filled-in circles) of a pitch while Pfx_z is the vertical break (the open circles). These values are both relative and compared to where a pitch thrown the same way as the pitch in question, but without any spin would end up. I'm not totally sure what you mean when you say Pfx_z is when the ball starts to break, and I think that the PFX value given in the Gameday app is the pythagorean sum of the two vectors. PFX^2=(Pfx_x^2)+(Pfx_z^2). I have some trouble wrapping my head around what PFX itself means, and prefer to use the two vectors.

Break Length is the field I used when talking about Lowe's curveball. It's the max height of a pitch over an imaginary line from release point to home plate. The MLB Gameday blog has the exact definition. Barry Zito's curve would have a high break length, while an ordinary fastball wouldn't. I haven't taken the time to find out why, but some sidearmers/submariners have very high break number, maybe because their release point is so low.

Wakefield ruins the idea of where a "non-spinning" pitch would end up, as his pitches don't spin, but end up in random places. His pitch charts are weird/interesting to look at.

What do you mean about actually modeling the path of the pitch? That sounds pretty cool to take a crack at.

You should be able to create an accurately animated model of the path of each pitch using the new gameday data. You could animate it from the point it leaves the hand to the point it reaches the plate, perhaps from different views. I think it would be an intuitive way to present the pitch data, and doesn't seem like it would be too hard to do. You could do side by side animations of pitches from various pitchers, to get a real-time idea of how they compare. Or you could compare the same pitch from two different pitchers, or two different pitches from the same pitcher, and probably plenty of other reasons. What I think would be neat is an animated model of a 3D baseball, and show the batters view, the pitchers view, as well other views. I think it would be really cool to do the same sort thing with the hittracker data.

Data on Matsuzaka and Wang would be really interesting.

Is the pitch classification correct? I would have thought the curve would have had a lot more movement than is suggested by the blue dots on the graphs. Couldn't those blue dots be change ups?


I've gotten a couple of questions about the classifications of pitches and after reading them, looking some other pitchers, I think I made a mistake with classifying some of the pitches. For Lowe and Cook, they both throw sinkers, change-ups and a breaking ball, a slider for Lowe and a curve for Cook. I made a mistake in thinking they both had two breaking balls. The black dots for both pitchers are in fact change-ups, and not a second breaking ball. The change-ups move similar to the fastball, which makes sense from a deception point of view.

The blue dots are the breaking ball for each pitcher. These charts aren't totally intuitive to read, because they are relative to a pitch that without spin. The blue dots don't mean that the pitch had no movement, but rather, they ended up where a pitch without spin would have. The break length essentially measures the highest height of the pitch, and Lowe's slider (I say curveball in the article) has the highest break length for any of his pitches, so he does have movement on the pitch. Lowe's slider might end up roughly where a non-spinning pitch would, but it has movement on the way there.


Wang made his only start of the season so far in TB, which doesn't have the system and the one start I have for Matsuzaka looks like Webb's, with dots all over the place. For whatever reason, the system has been installed in only a handful of stadiums so far, and even where it's installed, there are sometimes inconsistencies, although based on the number of pitches that some announcers credit Dice-K with, it might not be a problem in his start.


Thanks for that. I hear you on the break length. I'd have thought that a curve would have had a lot of 12-6 spin on it, thereby meaning it would drop a lot more than a pitch with no spin? Is this wrong ... why you imply by the break length would seem to indicate so