Trevor Bauer: Towards Better Pitching Through Science
Before anybody snarks about the quality of Trevor Bauer’s pitching, and whether or not he’s good enough for us to value his thoughts on pitching, know that he’s fully aware of his limits, and was even before conceding six runs to the Yankees last night.
“I don’t throw hard enough. My pitches aren’t strikes often enough. My pitches aren’t consistent enough. I’d almost rather not be a pitcher than be a mediocre pitcher,” he admitted to me. (I had to tell him he was decidedly above-average when it came to whiffs and strikeouts, at least.)
But this is exactly what makes him well qualified to study the art of pitching. He isn’t blessed with a Felix Hernandez changeup, or Clayton Kershaw‘s command, or even teammate Corey Kluber’s breaking ball. He knows that.
And so what brings him satisfaction? Studying pitching. Working hard to figure things out. Getting better, with the help of our best tools.
And if you don’t think he’s gotten better, it’s probably a matter of perspective. “I’m not the same pitcher I was last year, and I’m not the same pitcher I was at the beginning of the year,” Bauer said before a game with the Athletics. “I’m a much better pitcher subjectively this year, if not objectively. Changes and improvements are not always linear. Things may not show up this year but they still happened this year. And then if they show up next year ‘oh he figured it out!’ The fact that I’m doing certain things now can set me up to improve.”
Bauer does his best to be objective about pitching, but he also knows his limitations. For everything he’s discovered, he’s uncovered more questions on the same subject.
Take spin rate. The pitcher installed a TrackMan unit in his house. That’s serious work, and expense, done in order to “figure out how to train in order to spin the ball better.” He wanted to know how to change spin, and what spin would do to pitches (what it does to results is the step after). And he’s used those findings this year, for tangible results.

Minimum 200 thrown, Bauer’s curve is second among starters in swinging strike rate.
He says it’s because how he uses it, not the movement.
“Anything you release from max supination to neutral, actively trying to pronate is going to increase the spin rate,” he said. Turn your wrist like you’re opening a doorknob, and you’re supinating, so he’s talking about breaking pitches, mostly. “Any breaking pitch — a curveball, slider or cutter — turning it over will increase the spin rate, which is what you want because it will make the ball move more.”
You might do a double take here. Most people think that you pull down on a curveball on the outside of the ball, but what Bauer is saying is that you get more spin on your curveball if you pronate it, if you pull down on the inside more or less. If this is confusing, check out this GIF made from Bauer’s YouTube presentation on the subject. Watch the action on Bauer’s wrist as he releases the breaking pitch, more than what happens in the fingers.
So, yeah, a right hander’s wrist moves towards the left on a curveball release, and if you actively try to move it in that direction, you get more spin, and therefore more movement on the curveball.
Using PITCHf/x spin rate, I found that spin rate explained 22% of the variance in curve drop, so there is corroboration for Bauer’s findings. And you can see that Bauer has used these findings to increase the spin on his curveball, and the movement on the curve, though not the drop.
| Year | Curve Spin | Curve Drop | Curve Run |
|---|---|---|---|
| 2012 | 1369 | -9.5 | 3.1 |
| 2013 | 1590 | -9.5 | 4.7 |
| 2014 | 1705 | -8.3 | 5.2 |
| 2015 | 1711 | -8.1 | 5.8 |
Bauer also found similar findings for changeups. “Anything you release from neutral to max pronation, actively trying to pronate decreases spin rate,” doctor Bauer said. “So for changeups and split fingers and screwballs, if you actively try to turn it over, it’s going to decrease spin rate. Which is in line with what you want, because that ball will sink more and not rise as much.”

The new two-seam changeup grip with the fade and the drop.
Once again, we can see the effect of Bauer’s work in his changeup. (He also switched from a four-seam to two-seam grip, which helped him get more arm-side fade.)
| Year | Change Spin | Change y-mov | Change x-mov |
|---|---|---|---|
| 2012 | 1610 | 8.2 | -4.0 |
| 2013 | 1634 | 8.6 | -4.6 |
| 2014 | 1536 | 7.5 | -5.2 |
| 2015 | 1452 | 4.7 | -6.7 |
We know that high-spin fastballs rise, but how to manipulate that spin eluded Bauer. His spin rate on the fastball is up, but he doesn’t know why. “I wasn’t able to figure out anything to increase fastball spin rate,” he shrugged. “I tried. I tried different grips. I tried pine tar. I tried fatiguing the forearm to see if it would decrease the spin rate. I tried thinking about spin and trying to spin it. I couldn’t find anything.”
When Bauer talks about improving in ways that don’t necessarily show up in ERA, his increased spin rates are the kind of thing that he’s talking about.
And yet, it’s hard to make improvements stick. For example, look at the horizontal movement on his two-seamer this year.
He started the year regularly getting 10 inches of fade on the pitch, and now he’s down two inches. Is this a case of reverting to his old habits? “I’d assume so,” sighed Bauer. “That’s a question every pitcher has at some point. Why isn’t my ‘this’ moving? I’ve seen people throw a slider for the first time in their lives and say ‘hey that’s a good slider’ and then a month and a half later it’s gone and they can’t figure it out for a year and a half.”
That’s something I’ve heard before. Justin Masterson told me he had a changeup once: “When I went to instructs in ’07 I started throwing a changeup there, it was great, it had good action, hitters were getting out on the pitch, it was really effective. I went into my first offseason and I forgot. I’d never had an offseason like that before, I didn’t do any throwing, I didn’t think about it. All of a sudden, it was gone and I was like… I, I’m, pretty sure I held it like this,” the former Indian told me in 2013. He’s thrown over 20,000 pitches since then and hasn’t had a good changeup, by his own admission.
For Bauer, it’s a source of interest and confusion. He’s gained and lost his split-finger repeatedly over the last few years. And his cutter. And it’s not clear why. “Maybe my shoulder isn’t getting that full rotation, or something about how the ball is coming out and the spin axis on the pitch that goes away,” he wondered.
And video isn’t necessarily going to help. “Are you going to get an exact angle from the beginning of the season and now? You have parallax error,” Bauer pointed out. “The only way you could really do it is to shoot a thousand frames a second from literally the exact same location.”
If that sounds possible, it’s still hard, even with Cleveland offering something of the sort. “Even when you look at the video, you can say, on one of those my shoulder was here, and one of them it was here, but why? And is that responsible for why my curveball is not breaking as much?” There’s very little that’s scientific about body position in the same way as Bauer has been with pronation and spin rate.
And that’s too bad, because obviously the body is important. Not only for results, but for deception. Batters use body cues to anticipate the pitch, much like tennis players do. Bauer told the story of table-tennis master Matthew Syed playing Michael Stich on a tennis court. Here’s an excerpt:
In 2004, as part of a promotional event, he had the opportunity to play tennis against German tennis star Michael Stich, and asked Stich to give him a “real” serve rather than the soft serves normal for these sorts of events. Syed describes how the tennis ball flashed by before he had even started to respond – it took less than half a second to go from Stich’s racket to the other end of the court. Syed could read his opponents in table tennis, in which the response time is even shorter, just a quarter of a second, but hadn’t developed the skills to do this in regular tennis. Anyone who is highly skilled has the mental ability to “chunk”, namely to grasp a pattern of elements, make sense of it and immediately act on it.
Bauer lamented the fact that we don’t have good systems in place to track the movement of the body. “Even if I can master six different feels for six different pitches,” he wondered, “which is more important? Having three average pitches but they all look exactly the same or having six pitches with different release points where hitters can start to identify them? Having your body look different is the hitter’s first indication of what the pitch will be before the pitch is thrown.”
Cues from the body help hitters figure out what’s coming, subconsciously. And so it’s extremely difficult to study what we might call “deception.” And until we do, pitchers will wonder, as Bauer does: “Is getting the run on the two-seamer and the drop on the curveball more beneficial than having all my fastballs and curveballs look the same coming out? How do you weight those, what’s more important? Who knows?”
And as much as Bauer would like to be scientific about his approach to pitching, there’s much that’s left to feel on a start-to-start basis.
Take the splitter. “Sometimes the splitter cuts,” he admits. “Sometimes I’ll throw’em and it’ll really run; the majority of the time it floats or cuts. That pitch is interesting because you’re destabilizing the spin axis, so it’s not a pitch you can command.”
But even pitches he can command sometimes, if he doesn’t have the feel for them at that exact moment, he’ll start to manipulate the pitch. That’s happened some with the splitter, too. “You might manipulate it because it’s not feeling good and now the ball just floats,” Bauer says, frustration obvious. “It’s hard to replicate the spin axis and release each time.”
And yet those pitches that he’s not throwing so much right now, they still will be useful someday. “Those are going to be valuable pitches for me because at certain times you can use them and they will be beneficial,” Bauer said. Take the screwball. “If you throw a fastball in to a righty and he fouls it off, and then you throw a screwball in, he sees fastball and he tries to swing and then maybe you get a broken bat or whatever.”

The screwball. Watch the thumb. It’s like a two-seam cutter grip.
Command and ease in replicating means that he won’t go there often right now. “Until you have enough command of it to replicate it, it’s a risky pitch. Even with two strikes, I’d much rather throw a ball that I know will end up in the dirt then risk something else,” he said. “Those are pitches that I’ll throw more as the years progress.”
Recently, Bauer’s command numbers have gotten better. In July, at least, he walked only a batter and a half per nine innings. Bauer changed when he worked out using weighted balls some, but he also decided to stop throwing off of flat ground. “I don’t throw flat ground any more because the timing on the pitches and the movement is so different on the mound,” he says, and it’s hard to disagree.
In any case, Trevor Bauer is obviously a work in progress, and he still runs into bad days. Don’t say he’s trying to define himself, though. “I balk at the term ‘define,'” he interjected. “Pitching is so liquid. I’m not the same pitcher I was last year, and I’m not the same pitcher I was at the beginning of the year. I will be a much different pitcher next year. It’s all about how much you work on things.”
One thing we know for certain, though, is that he’ll read up, he’ll test the assertions, re-evaluate his hypotheses, and then apply the findings to his craft. What more can you ask of a pitcher, in the end. He can’t change his natural talent. And tinkering is fun.
With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.


Well done, this may be my favorite fangraphs article ever.
This was a tremendous read. As an Indians fan, Bauer means a lot to me, and I love getting insights like these into what he’s thinking about and trying to do.
Really good stuff, thanks Eno.
That’s an old baseball he’s gripping. Bill White!
My friend Luis in the press box gave me that for grip pictures… and somebody noticed, which is kind of awesome.
I was thinking the same thing! At first I wondered why the ball was so worn, then I just figured that there are probably MLB quality baseballs all over clubhouses, plenty of which must be worn from general use or something… basically I starting overthinking about that ball for no particular reason, but perhaps it was because everything about this article was interesting!
And I’m now realizing just how old that ball is… wow that’s awesome.
Really enjoyed reading the article, thanks! Even though I didn’t get all the terminology, it was very interesting.
Since part of the article’s topic is sort of on muscle memory and learning, thought you would be interesting in this article, ICYMI: http://gladwell.com/the-art-of-failure/
Talks about the two systems, explicit learning and implicit learning. I think the issue of the explicit learning taking over affects a lot of baseball players. You see it when a player would talk about simplifying things to “see ball, hit ball” or about how they stopped worrying and let God take over or when a player suddenly can’t go a basic thing like the catcher returning the ball to the pitcher or the pitcher unable to throw to a base, they are thinking too much and the explicit learning system takes over, but when they stop thinking about it, their implicit learning system is controlling things.
Bauer seems like he is one of those thinkers, from this article, and I wonder if this affects him in games, which could result in a poor start. Not that I was great or anything in my youth, but I could field OK on the practice field, got me the 3B job on a team, but it was lunchtime baseball and everybody was out there, and suddenly I was throwing balls that even Wilt Chamberlain would not have gotten, and I soon returned to fielding the pitcher’s mound. So I’ve seen what it can do to a person, and I think that sometimes ballplayers overthink things too much once they get on the field.
For such a talented, hard-working pitcher, this guy is up in his head too much. That might be why he so often loses his groove on the mound. Somebody who knows him needs to hand him the Inner Game of Tennis by Tim Gallwey.
Trevor makes me feel illiterate.
Trevor makes me feel a little red too.
He really hits home with the sentiment that pitching is “liquid”. With my my ups and downs playing sports growing up, I wish I’d heard more that even the greats are grasping at sand sometimes.
The realization that you’re just a Theseus’ Ship of cells can really help you get over the fact that improvements aren’t linear or guaranteed or visible at any particular point. Good life lesson too.
Awesome article, Eno.
Trevor Bauer: Vorsprung durch Technik
this is why I’m a big believer in Bauer. I really do feel like it’s only a matter of time until he reaches stardom.”I’d almost not rather be a pitcher than be a mediocre pitcher,” Great quote, it’s the thinking all the greats have.
How about better pitching through chemistry, though?
medicinal chemistry
I’ve always felt a little bad for Bauer, because he has all these ideas, and in addition to that I think his stuff is very good, and it must be really frustrating to have good stuff and a good process, and still get mediocre results. It seems like the pitchers who have good results just have an intuitive sense of how to approach batters, and there’s no way to abstract that into a theory. Or, at least that’s how it feels.
I wonder if he’s ever talked to Zack Greinke. I feel like those two would have a whole lot to talk about.
Might be evidence for mediocre process and/or stuff, no?
I think stuff can be measured pretty objectively, so I don’t think that’s the problem. As for process, absolutely it could be the problem. That’s why I say, it seems like the players with the best “process” sometimes just have an intuitive sense of what to do – how to approach hitters if they’re a pitcher, or what they think the pitcher is trying to do if they are a hitter.
Man, i wish fangraphs (or even the internet) was around when i was a high school pitcher.
Aren’t you tad old to be going shirtless!
Eno – this is excellent stuff
I really like his ideas about release point versus stuff. I bet it won’t be long before teams are using behind the plate cameras to analyze and quantify differences in batter view for various pitches, and coaching players to be as similar as possible across their repertoire (if they don’t do this already).
BTW, it takes a loooonng time to be able to throw a curveball that way. But much better for the elbow than more traditional approaches.
Eno, love it when you and Kyle twitter at each other.
I can unequivocally state that this is the first time I have ever seen the word “parallax” in a baseball context: amazing
That story about Justin Masterson’s change is so sad.
I love having Bauer in the game… I know he’d rather be great than smart, but to a fan he’s a fascinating pitcher to follow anyway.
The main reason the D-backs traded Bauer was that he refused to take direction in terms of how to pitch in lieu of his own “theories”.
His peripherals are improving. At this rate, he’ll be a consistent mid-rotation starter by 2018.
Did anyone else think it was kind of weird that Bauer is holding a William White Official National League baseball (which is very possibly older than Bauer himself) in the photo demonstrating the screwball grip?
Screwball, indeed.
Clearly jwpepa did, and I missed it.
He is like Jekyll and Hyde. Either good or very bad. Over his last 11 starts before the Yankee disaster he had a 5.25 ERA with about 2 HR/9. Kind of like CC Sabathia, except CC is more consistent and keeps his team in the game more often. Francona should have the bullpen warm up in the first to see which Bauer shows up because the bad Bauer can put a game out of reach real quick.
Bauer knows science other than that which he drops.
is he dropping science like galileo dropped the orange?
Awesome read.
Also, I had no idea that you could throw a curveball like that. Completely counter-intuitive to me.
How did you think it was thrown? I’ve tried to screw around with a curveball for a while, and nothing I tried worked until I basically did what Bauer does.
Rotating your wrist the other way. That was the way I always threw it, anyway.
Yeah I have since tried it and it just feels counter-intuitive. Have to fight the natural urge to tilt arm side.
Ugh, what is this guy on about? Where’s the grittiness?
Fantastic article, Bauer has to be one of the most thoughtful players in the game.
His rap songs agree.
This was so god damn great Eno.
Trevor Bauer is clearly overthinking his pitching. One thing to analyze what you’re doing. Another to be meddling with it during season.
Could Bauers struggles be because he’s constantly is trying to adjust his mechanics?
He was considered a big talent a couple of years ago. Not so much these days.
Of course he’ll get rave reviews with the nerd crowd. But considering he was drafted number three in the very strong 2011 class, he is not impressive.
Good, serviceable yes. Not much more.
Been a Bauer fan ever since I read this article about his use of Effective Velocity.
It’s a great way to think about pitching, and Bauer seems astute enough to pay attention to any way he can improve.
bauer needs to watch this scene over and over again til he internalizes it.
https://www.youtube.com/watch?v=WvzgRhBYgho
stop thinking about pitching and pitch.
also- an issue with trying to make lots of conscious changes in a short period of time, is you can have difficulty rationalizing what works and what doesnt. then you get caught up into a whole series of personal mind games. i went through a period like this with golf and once i just stfu, swung, and trusted my body to make the accurate corrections over time without constant conscious thought, i improved. now obviously this has limits, but over-analyzing is awful
I think I should have made this more clear but most of this stuff is done in the offseason.
Check out the folks at Driveline Baseball if you’re interested in more of this kind of stuff. Carson Fuller is cut from the same cloth
Fulmer, stupid autocorrect
I’m a little worried about his emphasis on pronation from a biomechanical perspective.
Care to elaborate for those of us who come out of the social sciences and/or humanities?
Bauer’s pitching IQ is tremendous, and this great article proves that-thanks Eno.
I wish there was a rec/like button on Fangraphs articles.
I remember seeing Kershaw in slow motion and he pronates an insane amount. Makes sense and I remember reading that to be better on your elbow. Seems like it’d be worse on the shoulder though.
Eno, I did some work recently with regression models predicting movement based on velocity, spin rate and spin direction. My dataset was from baseball savant, but I think these parameters are taken directly from mlb gameday and thus standard across sources.
The horizontal break on a pitch can be modelled almost perfectly (r-sq > .995) with the following term as the independent variable:
sin(radians(spin_dir))*spin_rate/(starting_speed^2)
For vertical movement, you just switch to cosine of the direction instead of sine. Loved this piece, hope this helps you.
Response to Jim Kelley: The reason why R^2 is essentially 1 is that PITCHf/x uses the following algorithm to calculate spin from the movement: spinrate=constant*movement*speed. Inverting that, we get exactly your expression relating movement to the ratio of spinrate to speed. The sine or cosine terms simply project out the direction of the spin axis, which in turn determines the direction of the movement. So, it is no accident that R^2 is so large.
Yeah I was afraid of reverse-engineering that calculation and tried to put in caveats both times I referenced my finding about spin and drop. Wish I had that TrackMan data…
Good to know, thanks for clarifying Alan.
When the broadcast teams show spin rate rankings for pitchers, are these typically calculated or observed?
As a Bauer fan, I think you might be underselling his “stuff.” Sure, the command is shaky at times and he doesn’t have a 100 MPH fastball, but he still has good stuff – as shown by the fact that he was drafted 3rd overall.
I’m also curious where the spin rates came from. That isn’t available at brooksbaseball or fangraphs right?