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Pitch Atlas

Breaking ball

Not a pitch

Knuckle-Slurve ("knuckleslurve")

aka knuckleslurve

Not really its own pitch. It's a casual mashup name for something sitting between a spike curve and a slurve. No tracking system recognizes it, so whatever gets called this would just register as one of those two.

Schematic baseball cover. This pitch has no filed seam geometry yet; the grip and shape below are sourced in words, not measured here.

The grip

There is no established grip, because this is not a recognized pitch. The name is a casual mashup of the two real pitches it sits between — the knuckle-curve (spike curve) and the slurve.

Reputable analysisKnuckle-curve (KC) — MLB.com Glossary, Pitch Types

No pitch-tracking system (Statcast or otherwise) carries a 'knuckle-slurve' or 'knuckleslurve' classification. It is a colloquial blend of two real, separately classified pitches, not its own pitch type. Sourced as the honest verdict; the two component pitches are documented (knuckle-curve at MLB.com, slurve as a 2023 Statcast classification).

What it does

No tracking system measures a distinct 'knuckle-slurve' movement profile because it isn't a classified pitch; any pitch labeled this way would actually register as a knuckle-curve or a slurve.

Reputable analysisSlurve (SV) — MLB.com Glossary, Pitch Types

Verdict, not a measured claim: the knuckle-slurve sits between the knuckle-curve and the slurve and is recognized by neither MLB Statcast nor any other classifier as its own type.

What it really is

A casual hybrid name occupying the space between two real, classified pitches: the knuckle-curve (the spike curve) and the slurve. It is best understood as either of those, not as a separate pitch.

Reputable analysisSlurve (SV) — MLB.com Glossary, Pitch Types

relationship -> knuckle-curve + slurve. Neither MLB nor any tracking system classifies a 'knuckle-slurve'; this is the honest 'not a pitch' verdict.

Who throws itNone — not a classified pitch

Study this first

No tracking system files this name. Whatever gets called a knuckle-slurve registers as a knuckle-curve or a slurve, and the knuckle-curve functions as a curve, so the filed 12-6 Curveball is the closest real pitch on the board.

Reputable analysisKnuckle-curve (KC) — MLB.com Glossary, Pitch Types
Filed specimen12-6 curveball

Basic file

This pitch has a sourced one-line grip and movement and an honest explanation, not yet a filed specimen with authored grip geometry and a full craft chapter. A fuller breakdown is coming. Sourced, not corrected.

Others in the breaking ball

SliderGyro Slider (Bullet Slider)SweeperSlurveSlutter (Cut-Slider)Curveball12-6 CurveballKnuckle-Curve (Spike Curve)Slow CurveScrewballSlip PitchDeathball

Everything above wears its source. When you want the set again, start at the front door: the Pitch Index.

“The part of pitching that separates the stars from everyone else is about 90 percent mental. That is why I considered it so important to mess with a batter’s head without letting him inside mine.”
Bob Gibson · Slider
Pitch Atlas

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pitch-atlas.comSourced, not corrected

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