Intermediate

Sinker (twee naden)

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

Definition

De two-seam fastball wordt langs twee naden vastgehouden en beweegt doorgaans naar de werparm-zijde en omlaag, wat eerder grondballen dan strikeouts oplevert.

Door de bal langs de smalle naden vast te houden vermindert de backspin en ontstaat er beweging beïnvloed door topspin. Het resultaat is een bal die doorgaans 1–4 mph langzamer is dan de four-seamer van de werper en naar de werparm-zijde breekt terwijl hij zakt. Werpers die op grondballen sturen waarderen de sinker, omdat zwak contact laag in de zone makkelijke outs oplevert. Het bewegingsprofiel verschilt sterk per armhoek — hogere armhoeken geven meer horizontale beweging; lagere armhoeken geven meer verzakking.

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

Hij leunde op zijn two-seamer en wist 58% grondballen af te dwingen door consistent laag in de zone te werken tegen rechtshandige slagmensen.

Why it matters

Het onderscheid tussen je two-seamer en je four-seamer in de analyse is cruciaal — SwingVantage kan signaleren of je releasepunt inzakt en twee ballen die van elkaar zouden moeten verschillen, laat vervagen tot één.

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.