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.

We hoped you liked reading Trevor Bauer: Towards Better Pitching Through Science by Eno Sarris!

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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.

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Thiago Splitchange
Thiago Splitchange

Well done, this may be my favorite fangraphs article ever.