Editing Curveball (section)

==Variations==
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Curveballs have a variety of trajectories and breaks among pitchers. This chiefly has to do with the arm slot and release point of a given pitcher, which is in turn governed by how comfortable the pitcher is throwing the overhand curveball.

Pitchers who can throw a curveball completely overhanded with the arm slot more or less vertical will have a curveball that will break straight downwards. This is called a [[12–6 curveball]] as the break of the pitch is on a straight path downwards like the hands of a clock at 12 and 6. The [[Rotation around a fixed axis|axis of rotation]] of a 12–6 curve is parallel with the level ground and perpendicular to its flight path.

Pitchers throwing their curveballs with the arm slot at an angle will throw a curveball that breaks down and toward the pitcher's off-hand. In the most extreme cases, the curve will break very wide laterally. Because the slider and the curveball share nearly the same grip and have the same unique throwing motions, this curveball breaks much like a slider, and is colloquially termed a "[[slurve]]". The axis of rotation on a slurve will still be more or less perpendicular to the flight path of the ball; unlike on a 12–6 curve, however, the axis of rotation will not be parallel to the level ground. With some pitchers, the difference between curveball and other pitches such as slider and slurve may be difficult to detect or even describe. A less common term for this type of curveball is a 1–7 (outdrop, outcurve, dropping roundhouse) or 2–8 (sweeping roundhouse curveball).

A curveball that spins on a vertical axis perpendicular to its flight path, producing complete side spin—3–9 for a right-handed pitcher or 9–3 for a left-handed pitcher—is commonly referred to as a sweeping curveball, flat curveball, or frisbee curveball. While this pitch still drops due to gravity, the absence of significant topspin results in less vertical movement compared to other curveballs, such as the 12–6, 1–7/11–5, or 2–8/10–4 varieties. Side spin typically occurs when a pitcher throws with a sidearm or low three-quarter arm angle, though it can also result from a higher arm slot if the pitcher twists their hand, causing the fingers to move around the side of the ball rather than over the top. This twisting motion is believed to increase the risk of arm injuries, particularly near the elbow.

By contrast, a slider’s spin axis is nearly parallel to the ball's flight path, similar to the rotation of a football or bullet, but slightly tilted upward toward 12 o’clock. When the spin axis shifts to 1 o’clock or 2 o’clock, the pitch becomes a slurve. A slurve often occurs when a pitcher applies excessive force to a curveball with insufficient finesse, resulting in a slight pronation at the release point rather than a full supination. Alternatively, a slurve can develop from over-supination when throwing a slider, leading to what is sometimes referred to as a "slurvy slider." A slurvy slider thrown with the same velocity as a power slider (typically 5–8 mph slower than a fastball) may exhibit greater lateral break.