Zack Greinke on Curveballs

Earlier in the week, we talked about the evolution of Zack Greinke‘s pitches. Mostly the piece was about the dalliance of his slider and his cutter over his career. Left on the cutting room floor was a mini conversation we had about his curveball. It didn’t fit the narrative because it wasn’t about an adjustment he’d made. But what he said did send me on a journey through the numbers.

Turns out, Greinke’s curve — despite being his third-best pitch and owning average peripherals — improves when compared to its true peers.

First, what the pitcher said about curves generally and his in particular. He thought the pitch wasn’t great for whiffs in general because batters recognize it and “you don’t get many swings.” The curveball gets the lowest swing percentage in baseball.

But trying to get called strikes on the curve is problematic, too. “My curve is so slow, that they might say ball, and if not, they can still react to it,” Greinke said. “[Justin] Verlander’s is so sharp that by the time they realize it’s a strike, they can’t swing at it.” To some extent, the pitcher was right — the fastest 30 regularly-thrown curve balls last year had a 20% called strike percentage, while the slowest thirty only showed a 17% number (Greinke’s came in at 16.7%). Not a big difference, though.

He felt the pitch was a good change of pace because it was a slow curve — it averages just over 70 mph these days — and it caused the batter to be out in front of the pitch. But he wasn’t sure if that was why curves turn into grounders. “The number one thing for curves and grounders — they are low in the zone,” said Greinke of the pairing.

All low pitches turn into grounders more, but it’s particularly true of curve balls, but not in the way it may first seem. 48.7% of all curves get grounders. Curve balls in the bottom third of the zone (and a little below) get grounders 48.2% of the time. But almost half the total curve balls land in that bottom third, so it’s hard to separate out the effect from the fact that most curves show up there.

One thing that becomes obvious is that velocity helps curve balls as much as it helps other pitches. Take a look at how the regularly-thrown fast and slow curve balls from starters fared in 2013:

Velocity GB% swSTR%
Sample 76.9 0.474 0.112
Fast CB 81.5 0.494 0.141
Slow CB 72.0 0.438 0.110
Top-50 GB% 77.8
Top-50 swSTR% 78.3

If you look at Greinke’s curve ball among the population of curve balls, it’s not super impressive. At 10% swinging strikes and 50% ground balls, it’s almost perfectly average — 11% swinging strikes and 49% ground balls is average among all curves.

But if you look at Greinke’s curve compared to the other slow curves, it starts to stand out. The pitch may be his worst off-speed pitch, but that’s only because he’s got a wicked slider and an improving change-up. And really, his change-up is the newest kid on the block. When seen over his career, Greinke’s change may be slow, but it’s more effective than the average slow curve ball.




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Graphs: Baseball, Roto, Beer, brats (OK, no graphs for that...yet), repeat. Follow him on Twitter @enosarris.


9 Responses to “Zack Greinke on Curveballs”

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  1. Brad says:

    Is Greinke the pitching thinking version of Votto?

    +14 Vote -1 Vote +1

  2. Frank says:

    I could read a Zack on pitching column every day.

    +22 Vote -1 Vote +1

    • joser says:

      I hope he goes on to something after baseball that allows us that kind of intellectual pleasure. The temptation is to go for a commentary spot on TV, and nature of that job tends to those turn even the smartest person into a repetitive idiot.

      Vote -1 Vote +1

  3. MLB Rainmaker says:

    Phenomenal article. Very cool stuff.

    Really love that insight about the pitch and its outcomes from a practitioner. Greinke isn’t mining fangraphs trying to find these correlations (though appreciate you fact-checked it Eno), but from seeing the ball off the bat and reading hitters he picked it up.

    I always wonder how much of this type of stuff is codified in the body of knowledge for old-hat baseball guys, the scouts and baseball guys that Moneyball rags on. Detailed statistical analysis is great, but there’s a bit of “baby with the bathwater” that happens among stat circles when it comes to first-hand knowledge of the game and the old school scouting perspective.

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    • olethros says:

      Not to put too fine a point on it, horseshit. Moneyball doesn’t rag on scouts, and no one in stat circles is advocating throwing out the value of first hand knowledge and observation. If anything, the truth is far more tilted in the opposite direction.

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      • atoms says:

        It’s more the other way around; the stats enable us to quantify and validate (and sometimes invalidate, but I suspect it’s mostly validate) the first-hand knowledge of those who play and watch the game closely.

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        • joser says:

          And the existence of better stats enables us to better define the areas where we don’t know enough, and lean more heavily on scouts to fill those in.

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