Designing a 4-Seam Fastball
The 4-seam fastball is one of those pitches that every player learns to throw as soon as they're old enough to hold a ball. Whether its a 4-seam or a 2-seam, a fastball is the one that we should have the most control over and it is used to help maximize the deception of your offspeed pitches.
So what makes the best 4-seam fastball?
A 4-seam fastball has carry (positive vertical movement) and run (horizontal arm side movement). Ideally you want to see a spin efficiency over 80%, when measured by Rapsodo with the goal being 100% efficiency. When a pitch is thrown at 100% spin efficiency, it maximizes its speed and movement.
Spin Axis Goals:
The spin axis for a 4-seam fastball should be between 12:00 and 1:30. The picture to the right shows how to visualize spin axis on a baseball by using a clock as reference. The closer to 12:00 the pitch is, the higher the carry will be and the lower the run will be.
Should your tilt fall below 12:00, the ball will start to cut and slowly become a bad slider. This is because your fingers are "getting around the ball" more than staying behind it, which means your fingers are more on the outer half of the baseball. If your tilt starts to lean towards 2:00 you will see more run than carry, and your ball will move more like a 2-seam fastball.
Spin Efficiency Goals:
The higher the spin efficiency on your fastball, the better. Our goal is 100% every time we throw it. When that is achieved, we can maximize the pitch's speed and movement.
A fastball with a low spin efficiency will have drastically reduced movement. As the spin efficiency lowers, the ball will look like it is wobbling towards the plate. This causes the magnus force to have less of an effect on the ball and the ball will move less and a slightly slower.
Marco Estrada has some of the best vertical movement on his 4-seam in baseball. His fastball averages around a foot and a half of movement. That means that as the ball travels to the plate, on average, it is around 18 inches higher than it would be if only gravity affected the ball. You might also have noticed that he throws it at 86mph, significantly lower than some of the "best" fastballs. Estrada is able to generate above average spin and consistently hit that 12:00 spin axis helping him create one of the most effective 4-seam fastballs in the game.
Next week we will continue to discuss fastballs as we break down 2-seam fastballs and a few pitchers who have different yet effective versions.