What the Baltimore Bullpen Can Teach Us About Arm Action

“So you’re just studying oddity pitchers,” said Zach Britton over my shoulder as I took our conversation over to Darren O’Day. I bristled at the word oddity, because it implied some sort of freak-show gawking. “No! I’m into pitching, and you guys have interesting pitches,” was my earnest response. Eventually, most of the Orioles bullpen was in our scrum, talking pitching and pitches.

He wasn’t wrong, though. At the heart of that bullpen are three very… odd pitches. And checking out the three of them can teach us something about arm action.

Zach Britton’s Cutter Sinker
Take a look at Britton’s sinker grip and you’ll immediately know something strange is going on. That’s no two-seam grip.

Zach Britton’s Cutter Sinker Grip.

I mean, take a look at Jake Peavy’s cutter grip.

Jake Peavy’s Cutter Grip.

Britton’s sinker is almost the left-handed version of Peavy’s cutter grip.

Maybe that shouldn’t be surprising. The pitch is a result of his pitching coach in the minors, Calvin Maduro, trying to teach him a cutter. When they saw what was happening — “it was slightly unique” Britton said with a smile — they decided to run with it.

The result has been a pitch that almost defies classification. Look at its main features put up against the averages for a couple pitch types.

Zach Britton’s Sinker Movement & Velocity, In Context
Pitch Type avg(pfx_x) avg(pfx_z) Velocity
Britton’s Sinker 9.1 3.7 95.8
Four-Seam 5.5 9.4 91.2
Two-Seam 9.4 6.8 90.8
Sinker 9.8 6.1 89.8
Cutter 0.6 5.7 86.2
Split Finger 7.4 2.4 83.1
Slider -1.1 1.4 82.9
Sample: All lefty pitchers, 2015
avg(pfx_x) = average horizontal movement, in inches
avg(pfx_z) = average vertical movement, in inches (smaller = more drop)
Velocity = average velocity in mph

Britton’s sinker does have the arm-side fade of a two-seamer or sinker, yes. But it has even more drop than your regular cutter, and as much drop as some changes and sliders.

Take a look at the only other fastballs that have averaged 94 mph and also dropped anywhere near as much as Britton’s sinker. Remember that he’s the only lefty, so he should get about a mile per hour extra credit, since lefties generally throw that much slower.

Zach Britton’s Sinker Comps
Pitcher Throws count(*) avg(Pfx_x) avg(Pfx_z) avg(start_speed) GB% swSTR%
Sam Dyson R 509 -9.0 1.8 95.5 80% 11%
Zach Britton L 744 9.1 3.7 95.8 82% 14%
Carlos Martinez R 687 -9.3 3.8 94.8 64% 8%
Blake Treinen R 548 -9.7 3.8 96.3 69% 5%
Jim Johnson R 650 -8.6 4.9 94.3 63% 5%
Sample: All lefty pitchers, 2015
avg(pfx_x) = average horizontal movement, in inches
avg(pfx_z) = average vertical movement, in inches (smaller = more drop)
Velocity = average velocity in mph

You could say that Britton throws the righty version of the sinker thrown by Carlos Martinez, but even that doesn’t quite capture how effective Britton’s sinker has been. It’s clearly a rare pitch, even if there are two or three other right-handers that get similar movement and velocity. And by results, Britton is all alone when it comes to combining whiffs and grounders.

As for why the pitch ends up moving like that, Britton shrugs. “I try not to pronate or manipulate the pitch at all,” he said, “just grip it and throw it.” He acknowledges it looks like a cutter grip, and even admits that all he does to throw his slider is move the thumb in. So a big part is the grip, but it’s not all of it.

Why does he create a sinker with a cutter grip? “I think it’s unique to each guy. Maybe arm action?” was the best the pitcher could come up with. To compare, here are freeze frames at or near release for Zach Britton, Blake Treinen, and Sam Dyson.

Arm slots on release for Zach Britton (left), Blake Treinen (middle), and Sam Dyson (right).

While they’re all less than over the top, Britton’s arm angle doesn’t dip as much as the other two. By height-adjusted release point, Britton is four inches higher than Treinen, who is four inches higher than Dyson. So “arm action,” if it’s our answer, is not only about release point and arm angle.

Darren O’Day’s Submarine Riseball

We’ve talked about this pitch before, but not long after we debuted the Submarine Riseball, I got a chance to talk to the pitcher about his pitch. Turns out, it’s just a four-seam grip. Thrown in super slow mo from down below, here’s video sent by the pitcher himself.

Here’s another unique pitch — there might be another pitcher that throws a submarine riseball, but we couldn’t find one — and it’s not all about arm angle. There are other submariners, in other words, but no other PITCHf/x-era submarine rising fastballs.

When I asked about how he manages to get that movement, O’Day wasn’t sure either. “I spiral it, and that keeps it stabilized,” he told me before a game with the Athletics. “When I throw my slider, they look similar.”

He mentioned arm slot, but also finger action. The thing that makes his slider (left) and four-seamer (right) similar despite different grips is that they come off his middle finger. By releasing the four-seamer off of his middle finger, he gets the backspin that leads to that rare rising action.

Darren O’Day’s slider (left) and four-seam (right) grips, from his approximate arm angle.

Take a look at a still from the video above.

Darren O’Day’s middle finger is prominent as he releases his riseball.

So, to understand arm action, we also have to understand finger action.

Mychal Givens‘ Sidearm Cutter

There are other crazy sinkers (though not from a lefty), and there are other submariners (though not with rising fastballs), but you might be most surprised that there aren’t many other Mychal Givens types out there, either. Especially when you see it live — it looks almost unremarkable until you see how uncomfortable the hitters are.


Givens releases from a sidearm slot, sort of. And given that slot, his movement is surprising. Take a look at the few guys that release within an inch of his “true release point,” which is just a height-adjusted vertical release point. He’s got the “straightest” fastball.

Mychal Givens‘ Fastball in Context
Pitcher Height Average X0 Average Z0 True RP Avg (PFx_x) Avg(PFx_z)
Chris Sale 78 2.8 5.1 -16.6 11.4 5.8
Mychal Givens 72 -3.0 4.7 -16.0 -4.1 7.0
Louis Coleman 76 -3.9 5.0 -15.6 -4.6 7.9
Yimi Garcia 73 -2.4 4.8 -15.3 -6.4 7.5
Sample: All pitchers, 2015, within one inch of -16 True RP
True RP = height adjusted release point
avg(pfx_x) = average horizontal movement, in inches
avg(pfx_z) = average vertical movement, in inches (smaller = more drop)
Average X0 = average horizontal release point
Average Z0 = average vertical release point

Hence the hitters’ lack of comfort — they’re expecting a sidearm fastball with tons of arm-side fade, and they get something that almost looks like a cutter. “My pitching coach in Double-A used to say I’m a unicorn,” admitted Givens. “It’s weird,” said O’Day of Givens’ release. “He gets on top of the baseball from that low three-quarters slot.” Even though it doesn’t look like a three-quarters slot, you can understand what O’Day means.

Looks like a sidearmer, cuts like an over-the-topper.

So we have to add a third function to “arm action” — hand position. You can’t see in the picture above, but his hand isn’t parallel to the ground. As O’Day says, Givens gets on top of the pitch despite his arm angle.

Givens’ grips are standard, but his hand angle and arm slot combine to give him a unique look. Britton has a self-confessed “funky grip” with otherwise more standard release action. O’Day has the strangest release, and uses a different finger action to separate himself from the rest of the submariners. O’Day sums it up well when he says that pitch movement is “a combination of grips, hand size, finger length, arm length, and hand position.”

Grips are cool, but arm action is just as meaningful. And within arm action, it seems, we can include hand and finger action as well. Amazing what a few oddities — I mean, ahem, unique pitches — in the Baltimore bullpen can teach us about baseball.

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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8 years ago

that O’Day video is so awesome it should have been caught by my company’s porn filter

8 years ago
Reply to  johnnycuff

my forearm cringed when I saw that. The way his arm naturally rotates there is impressive.

Pirates Hurdles
8 years ago
Reply to  plasmaj

yeah, just mimicking that elbow roll over makes my elbow pop.