A.J. Burnett’s Not So Secret Weapon

The Pittsburgh Pirates are in a dogfight for the National League Central title, and the resurgent A.J. Burnett is a big part of the team’s success. Since coming over from the Yankees, the right-hander has put up close to 350 strikeouts with a near-3.00 ERA. All this, and he throws two pitches 95% of the time. Burnett knows he doesn’t have the largest arsenal — he enjoys his reduced repertoire — but that doesn’t mean he hasn’t added a few wrinkles as he’s matured.

Burnett says it all started pretty simply. He threw hard. “My dad wouldn’t let me throw anything but fastballs until I was 15 or 16,” Burnett told me before a game in San Diego last week. “My grandfather came over one day and said, `Hold it like this and throw the bleep out of it.'” Young A.J. threw the ball over the barn. After his grandfather chewed him out for his lack of command, the teenaged Burnett said, matter-of-factly, “I held it like that and threw it.”

The Burnett family knuckle curve

So it took a little practice, but he finally got a handle on the pitch. One key for Burnett is to dig a fingernail into the seam. And where you emphasize ‘coming over the top’ in a normal curveball delivery, the knuckle curve is a little different. Perhaps because only one finger is on the ball, and not two, the ball has nowhere to go but over the top with the traditional curveball spin. Burnett emphasized that you don’t release it like a curve — “You hold it like a gun” — and then you release it just like you’re holding it.

How you release the knuckle curve

When he came up to the big leagues, Burnett said the “2-2 changeup was the pitch of the millenium.” And here he was, all gas and bite. He hadn’t taken the time to learn one. He’s seen hard fastballs that didn’t get whiffs, but he didn’t have that problem and hadn’t turned to the changeup for a cure. Sure, he tried to learn one because everyone was doing it, but it wasn’t very good, and it didn’t have that 10 mph difference people look for. “I’m not going to throw a 91 mph changeup. I’m just not going to do it,” Burnett says. That’s why he throws “two changeups a game, maybe.”

To this day, teams know what’s coming when they face the Pirate starter: “They know I’m coming after you with the fastball and then I’m coming after with the hook. It’s no cutter, changeup; it’s you know, c’mon. Two things are happening: You’re trying to hit a home run, and I’m trying to strike you out. Only two things happening.”

But as he’s lost a little gas on the fastball — he’s down to 93-plus mph from 95-plus mph in his early days — he’s been forced to adapt. He’s stopped trying to throw 99 mph, and that’s meant he’s had to make changes. As he put it to a teammate recently: “It’s hard for hard-throwers to take a step back and figure out how to pitch again. You get away with so much more when you throw hard.”

One change in Burnett’s game has been in his fastball mix. He used to be all four-seamer, but now he’s established a 50-50 mix on his four-seamer and sinker. Throwing the sinker away to righties has become a first-pitch-strike approach for him. Two of his three best years in that statistic have come with the Pirates, and he says it’s at least partially due to throwing the sinker more often. But the sinker also gets three times the ground balls that his four-seamer does, so this new fastball mix is also part of why two of his three best ground-ball rates have come in Pittsburgh.

But even the knuckle curve itself has seen some changes over the years. You see, he really has two knuckle curves. One comes over the top: It’s slower, and it has a traditional curve-ball type drop. The other is more sidearm, It’s faster, and it looks like a slider. Take a look at his release points on all pitches classified as curves, knuckle curves and sliders. The color-coding reflects the pitches’ velocities.

Burnett’s 2007 to 2009 PITCHf/x curveballs and sliders by release point. Color coding by velocity (75 mph to 89 mph)

As we’ve learned before from others, pitches are really on a continuum. Just as Luke Gregerson has seven sliders or one slider, A.J. Burnett has two knuckle curves — or perhaps only one, depending on how you want to classify things. He says he uses the 84 mph to 85 mph one with the lower arm slot for more side-to-side movement. He uses the over-the-top, slower one for the big drop. Here they are in .gif, the over the top one on the left, the slider-like version on the right.


While he knows fooling with his release point can be dangerous — sometimes one of the two is “nowhere to be found” — he has modified his plan of attack over the years. If he establishes the over-the-top one first, the sidearm one usually follows.

But on some days, he has neither. Still, even his sense of competition has matured to the point where he can usually salvage an aspect of his game. “There are days when you are in that bullpen and you can’t wait to get out of there because you’re just terrible,” he says. “Can’t throw a strike. Early in my career, that was an uh-oh. Now I realize, I’m just down here getting loose. I don’t need to be perfect. As soon as you get on that mound and the hitter gets in there, everything goes away.”

Over the years, Burnett has changed his game a bit. He’s calmed some, he’s developed a second arm slot for his knuckle curve, and he’s embraced the sinker and the first strike. But, really, it’s still a simple game for Burnett. Where some pitchers have to think hard about their diverse arsenals, Burnett is “glad to have just a couple” pitches. “I can’t get in trouble thinking,” he says.

Wandy Rodriguez’s knuckle curve grip, by A.J. Burnett.

That simplicity might be why you’ll find that Burnett is glad to talk about his favorite pitch. The pitch that Sandy Koufax might have thrown; the pitch that Burt Hooton and Mike Mussina espoused; the pitch that Grandpa Burnett once showed 16-year-old A.J. That’s the pitch you’ll see Burnett talking about with Wandy Rodriguez, refining with Jeff Locke, and trying to convince Gerrit Cole to throw. The knuckle curve.

Thanks to James Santelli of Pirates Prospects for the second .gif above.

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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10 years ago

He looks so graceful in his post-k turn in the 2nd gif.

Love this series, Eno, keep pulling the curtain back for us!