Intermediate

Reta de duas costuras / sinker (two-seam fastball)

Also known as: two-seamer, sinker, 2 costuras

Definition

A reta de duas costuras é segurada ao longo de duas costuras e normalmente se move para o lado do braço e para baixo, induzindo rebatidas rasteiras em vez de eliminações por swing.

Segurar ao longo das costuras estreitas reduz o backspin e permite um movimento influenciado pelo topspin. O resultado é um arremesso que costuma ser de 1 a 4 mph (2–6 km/h) mais lento do que a reta de quatro costuras do arremessador e que quebra para o lado do braço de arremesso enquanto afunda. Arremessadores que buscam rebatidas rasteiras valorizam o sinker porque o contato fraco na parte baixa da zona produz eliminações fáceis. O perfil de movimento varia bastante conforme o ângulo do braço — ângulos mais altos produzem mais deslocamento horizontal; ângulos mais baixos produzem mais afundamento.

Beginner tip

Start by simply shifting your four-seam grip to the narrow seams without changing anything else in your delivery and let the natural topspin create movement before trying to add extra arm-side run.

Advanced note

Fine-tune the run-to-sink ratio by adjusting index-finger pressure. This means more index pressure increases arm-side run, more equal pressure with a downward wrist drive produces a truer sinking action.

Example

Ele viveu do seu sinker, induzindo rebatidas rasteiras a uma taxa de 58% ao trabalhar a parte baixa da zona contra rebatedores destros.

Why it matters

Distinguir seu sinker da sua reta de quatro costuras na análise é fundamental — o SwingVantage pode identificar se o seu ponto de soltura está colapsando e misturando o que deveriam ser dois arremessos distintos.

How it shows up on video

On video, the two-seam fastball should look identical to the four-seamer through the first third of flight. Divergence in trajectory becomes visible only in the final 15 feet. Common errors on camera include a change in arm action that telegraphs the pitch before release, a noticeable wrist roll that produces sidespin rather than the intended run-and-sink movement. A release point that drifts lower than the four-seam reference. This means blending the two pitches into one undifferentiated offering.

Common mistakes

Visibly changing arm action or wrist position when switching from the four-seamer to the two-seamer, telegraphing the pitch to attentive hitters
Releasing the ball with excess sidespin rather than the run-and-sink tumble, turning the pitch into a flat slider with no ground-ball value
Locating the two-seamer up in the zone where its downward movement is neutralised and its slower velocity becomes easy to elevate
Gripping the seams so tightly that arm speed drops, making the velocity gap between the four-seamer and two-seamer larger than intended and obvious to hitters

In SwingVantage Motion Lab

SwingVantage compares release point coordinates and wrist angle between four-seam and two-seam reps to verify that the two pitches share the same early flight path. A diverging release point or visible arm-action change between pitch types shows up immediately in the side-by-side rep overlay.