Intermediate

Fastball Dua Jahitan / Sinker

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

Definition

Fastball dua jahitan dipegang di sepanjang dua jahitan dan biasanya bergerak ke sisi lengan lempar serta menukik ke bawah, memancing ground ball alih-alih strikeout.

Memegang bola di sepanjang jahitan yang sempit mengurangi backspin dan memungkinkan pergerakan yang dipengaruhi topspin. Hasilnya adalah lemparan yang biasanya 1–4 mph lebih lambat dibanding four-seamer milik pitcher tersebut dan bergerak ke arah sisi lengan lempar sambil menukik. Pitcher tipe ground-ball sangat menghargai sinker karena kontak lemah di bagian bawah zona menghasilkan out yang mudah. Profil pergerakannya sangat bervariasi tergantung arm slot — sudut lengan yang lebih tinggi menghasilkan pergerakan horizontal lebih besar; slot yang lebih rendah menghasilkan tukikan lebih dalam.

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

Ia mengandalkan two-seamer-nya, memancing ground ball dengan rasio 58% dengan bekerja di bagian bawah zona melawan hitter tangan kanan.

Why it matters

Membedakan two-seamer dari four-seamer Anda dalam analisis sangatlah penting — SwingVantage dapat menandai jika titik pelepasan bola Anda mengempis dan mencampur dua lemparan yang seharusnya berbeda.

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.