For beginners, a curveball is a breaking pitch that has more movement and can deceive the baseball hitter. It is thrown slower than a fastball with more overall break than a slider. The significant movement with which a curveball arrives leaves the baseball hitters off-balance and forces them to swing too early or hit over the top of the curveball.
The spin imparted on the curveball creates unequal air pressure on opposite sides of the ball, which then pushes it away from its otherwise straightish path. The movement is a blend of deliberate deception and science. At the point of release, the pitcher imparts topspin on the ball. Later on, as the ball travels toward home plate, the spin that the ball is still carrying drags the air faster on one side than the other. The aerodynamic impact on the ball ensures its movement and can deceive the hitter by moving it away from the batter’s arc. The curveball is therefore one of the most fruitful pitches and tactics in baseball.
The Magnus Effect
Magnus Effect is the core scientific event that takes place behind the curveball and its movement. It is named after German physicist Heinrich Magnus, who first described and explained the effect in 1853. After a pitcher spins the ball to try and successfully execute the curveball against the hitter, the magic takes place in the air. When the ball spins through the air, its surface drags a thin layer of air along with it. The side on which the spin moves in the same direction as the airflow, the air around it is faster. Naturally, the airflow on the other side of the spinning ball is slower.
According to aerodynamics, the faster movement of the air exerts less pressure on an object. It is this pressure that performs the entire spin or the movement of the curveball for a pitcher, as pressure difference creates a net force that pushes the ball toward the low-pressure side. This force, or the pressure, pushes the curveball thrown with topspin downward before gravity takes over and makes the ball dive more strongly than the ball thrown without any spin. The Magnus Force is hence intrinsic to the entire execution of the curveball.
Pitcher
While the science and aerodynamics ensure the ultimate curve or spin on the curveball, the role of the pitcher in the entire event shouldn’t be underestimated. A pitcher must throw the ball with topspin to introduce the drop or movement that eventually deceives the hitter. The topspin is generated through careful hand movements along the ball.
At the point of release, a pitcher must position his hand slightly to the side of the ball. It ensures his fingers get in front of the ball and he can intentionally push it downward during the release. Among the fingers, the middle one does the most impactful part, yanking it down as it leaves. Because the wrist and fingers rotate forward over the top of the ball instead of staying behind, coaches often describe the curveball as a pitch thrown from the back of the hand.
A successful release of the curveball will result in a ball spinning rapidly along an axis which is close to perpendicular to its direction of travel. In baseball, the higher the speed of release, the more the Magnus force does its job efficiently. A quality curveball specialist usually imparts 2,400 to 3,000 revolutions on the ball per minute.
Seams
A ball used for baseball hitting would receive the curve even with a smooth surface. However, the presence of the seams further bolster the curve movement that occurs. The seams basically amplify the Magnus force and its effect to cause the deception against the hitter. Seams disrupt the airflow around the ball by creating greater turbulence and aggravating the air separation from the ball’s surface.
Over the years, the importance of seams on the ball deployed in baseball has attracted extensive research. According to researchers, each seam produces large disturbances in local air pressure. The seam and its position at certain angles can heavily influence the air pressure received and how both drag and lift are executed. In even simpler words, the seam keeps the airflow attached to the ball for longer and ultimately ensures a higher pressure difference for the Magnus effect to work perfectly. The presence of seams is also why the seam orientation of the ball can majorly impact a pitcher’s success rate.
From a hitter’s perspective, the curveball causes an optical illusion at the point of sighting the ball and hitting it in the intended direction. It creates a blur in the entire process by which our brain understands motion and responds accordingly.