너클볼, Knuckleball

손 끝으로 회전을 줘서 던지는 다른 공들과 달리, 손가락의 관절(Knuckle)을 이용해 밀어서만 던지기에 붙여진 이름이다. 즉, 공의 회전을 거의 없앤 구종으로, 둥실둥실 떠가며 무작위로 움직인다. 공의 회전을 최대한 줄여서 날아가는 동안 공 주변으로 발생하는 난류에 따라 이리 저리 움직이는 것이다. 축구에서의 무회전 슛, 배구에서의 플로터 서브처럼 유체역학에서 말하는 카르만 효과를 이용한 구종이다.

이렇게 공기 저항, 실밥의 위치, 하물며 공에 난 미세한 흠집까지도 관련되어 공의 이동이 결정되기에 던지는 투수, 받는 포수, 쳐내는 타자 그 누구도 예측할 수 없는 변화무쌍한 움직임을 보인다. 그래서 너클볼은 제구가 극도로 어렵다. 기본적인 직선 벡터가 있기에 1루나 3루 방향으로 확 틀어지지는 않지만, 까딱하면 폭투 나오는 건 일도 아니다.

구속은 상당히 느려서 일반적으로 시속 70마일(약 113km/h) 정도지만, 투수별로 편차가 있어서 R.A. 디키의 너클볼은 최고 81마일(약 130km/h)이 기록되기도 하고, 보스턴 레드삭스 스티븐 라이트는 70마일 중후반대의 너클볼과 60마일 중반대의 너클볼을 모두 구사한다. 하지만 이렇게 느려도 워낙 움직임이 변화무쌍하다보니 제대로 맞히기 쉽지 않고, 맞춰봐야 제대로 된 타구가 나오지도 않는다. 심지어 타자가 맞히려고 휘두르는 배트의 바람에마저 영향을 받기 때문에 맞힌다고 해도 타구가 좋게 뻗기는 어렵다.

너클볼은 일반 구질을 던질 때와 투구 메커니즘이 상당히 다른데, 일반적인 구종들은 손가락으로 긁어서 최대한 많이 회전을 가하는 느낌이라면 너클볼은 손톱으로 공을 미는 방식이다. 회전을 최소화하기 위해 어깨는 공이 미트까지 갈 정도로만 사용하고, 허리도 튕기지 않으며, 하반신도 거의 사용하지 않는다. 

 

 

 

Unlike other balls thrown by rotating with a fingertip, it is the name given to throwing only by pushing using the knuckles of the fingers. In other words, it is a ball that has almost eliminated the rotation of the ball, floats and moves randomly. It reduces the rotation of the ball as much as possible and moves here and there according to the turbulence generated around the ball while flying. It is a ball type that uses the Karman effect in fluid mechanics, such as a no-rotation shot in soccer and a float serve in volleyball.

Since the movement of the ball is determined by air resistance, the position of the thread, and even the slightest scratches on the ball, no pitcher, catcher, or batter can predict it. As a result, knuckleball is extremely difficult to control. It doesn't go in the direction of first or third base because there is a basic straight vector, but it's not a matter of wild pitches when you're stuck.

The speed of his ball speed is generally about 70 miles per hour (about 113 kilometers per hour), but R.A. Deekey's knuckleball can record up to 81 miles (about 130 kilometers per hour), and Boston Red Sox's Stephen Wright can play both the mid-to-late 70-mile knuckleball and the mid-60-mile knuckleball. Even at such a slow pace, however, it is not easy to hit the ball properly, and it is difficult to hit the ball properly only when you hit it. Even if you hit it right, it is difficult to stretch it out nicely, as it is affected by the wind of the bat that the batter is trying to hit.

Knuckle balls have a very different pitching mechanism than regular pitch throwing, and while normal pitch types feel like scratching with your fingers to rotate as much as possible, knuckle balls are a way of pushing the ball with your fingernails. To minimize rotation, the shoulder is only used to make the ball go to the mitt, the waist does not bounce, and the lower body is rarely used.