Knuckle-Curve (Spike Curve)

aka spike curve · KC (Statcast code)

A curveball with a firmer grip. You spike one fingertip into a seam for a stronger hold, which often gives a tighter, harder break. Despite the name it has nothing to do with a knuckleball, so most players just call it the spike curve.

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

Gripped and thrown like a curveball, but the index finger is spiked — the fingernail or knuckle dug into a seam and raised off the surface — giving a firmer anchor on the ball; the middle finger rests along a seam as usual.

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

What it does

Functions essentially as a curveball, often with a tighter, harder break than the standard grip. Despite the name it has nothing to do with a knuckleball, which is why players and coaches usually just call it the spike curve.

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

Who throws itOften called the 'spike curve' by MLB players and coaches

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.