Renaming the Rising Fastball

Tom Seaver’s passing made me recall a quote of his, “The good rising fastball is the best pitch.” My initial reaction when I read that quote is to stand out the Mount Newtown, reciting calculus that proves the quote wrong. Tom Seaver was one of the smartest pitchers that hoisted a ball towards the plate. Avoiding my rush to smear Seaver, I’ll try to determine what the elusive rising fastball is.

Announcers, managers, pitchers, and batters love to talk about a rising baseball. A pitch that defies gravity and rises on its path to the plate. There is no uniformity with these statements. Other people in the game never speak of a rising fastball and even dismiss claims about one.

Physics of a Rising Fastball

Take a half cup of physics, mix in a quarter cup of eye movements and sprinkle with other disciplines and we’ll bake up a simple model to explain a rising fastball. 

Is it possible for a pitch to rise during it’s trip to the plate? For that, let’s talk about physics.

There is considerable research on the flight of a pitched ball. If one wants to learn more about physics in baseball start with Dr. Alan Nathan and his Physics of Baseball page. I’ll provide a very brief overview.

Imagine a straight line path from the pitcher’s hand to the target the catcher provides. Unless you an alien, that straight-line path will include the effects of gravity, the ball will be moving towards the ground. Despite our best efforts, our arms are not able to put an object into orbit. Our minds naturally include that in our determination of the flight of things. 

The downforce caused by gravity on a five and one-eighth ounce baseball is about 0.33 pounds. For a ball to rise there needs to be a counterforce of 0.33 pounds to cause the ball to rise. 

Air is full of molecules and those molecules cause a spinning ball to interact with them. The interaction of the spinning ball with the air is called the Magnus Force. You can also consider it as the lift on the ball. The spin of the ball, both direction, and angle, will determine how the force will affect the ball. For maximum counter effects of gravity, a ball must have backspin rotating on an axis parallel to the ground. 

Yes, Yes, Yes. I am leaving a few things out. If the ball has front spin it will drop more. If the rotational angle is not exactly parallel to the ground the magnitude gets smaller. The purpose is to see if rising fastballs are possible in perfect conditions and that is a backspin with a rotational axis parallel to the ground. This also makes the equation must easier to calculate. 

There is a lot of math to calculate here, I’ll save you and just give you the answer, (i.e.: the equation I use): rpm = (130200*mph)/(6520 – (mph*mph)).

This will tell use the spin (rpm) we need to provide the need Magnus counteract gravity. Note, a negative spin means backspin. 

A 100 MPH pitcher would need a spin rate for about 5600 RPM to rise. Once we get to a reasonable spin rate, say 2300 RPM, the speed crossing the plate would be about 114 MPH and leaving a pitcher’s hand around 123 MPH. 

So, a rising fastball is possible if we could figure out how to throw a ball 123 MPH. Most people agree that 111 MPH is the upper limit that a baseball could be thrown. The theoretical golden pitcher would cross the plate at 103 MPH and require a spin rate of around 3300 RPM to rise. 

So, the rising fastball is not a myth, it is possible. It is highly unlikely that one has ever been thrown. But people talk about it. Why?

Remember how I asked you to visualize the path of the ball? It was a straight path and your mind will include the standard effect of gravity. Your mind and how we visually process the flight of a ball just may provide the answer. 

Can a Batter Believe Their Eyes

To follow the flight of the ball your eyes have to move. There are four types of eye movement. Saccadic eye movements for reading, looking for a spot at the bar, or finding your friend in a room. Vestibulo-ocular eye movements help you maintain your eyes during head movement. If you have ever stood on a rocking boat and looked at something onshore, these eye movements help you stay fixed on that something. Vergence eye movements help you transition watching something far away to being up close. Vergence makes it possible to see a building as a small object that you can cover with your hand to a large building that casts a shadow on the road. Smooth-pursuit movements allow us to track a moving object. 

A batter uses all of these when batting. The batter will need to find the pitch as it is leaving the pitcher’s hand. A batter’s head will move while he watches the pitcher and starts his swing. The ball is going to transition from being a small object far away while the batter is tracking the movement. During this time, the angle the ball appears to the batter also changes from nearly 0 degrees when the pitcher has it to 90 degrees when it crosses the plate. Also, the umpire is doing the same thing. 

The batter is processing all this while attempting to decide to swing at a pitch that will cross the plate in about .7 seconds, which is almost the same amount of time it takes the swing. The brain seems to have developed three strategies to follow the pitch. 

A batter may follow the pitch with their eyes for as long they can, with the head remaining stationary. The batter will lose sight of the ball about 12-10 feet in front of the plate. A batter can also move his head to follow the ball. In this case, the batter will lose sight of the ball about 5-7 feet in front of the plate. In both cases, the batter will often miss the ball crossing the ball or hitting the bat. For this type of batter, the location of the ball when it crosses the plate is unknown. The flight of the ball is well known though. 

The third type of hitter will follow the ball with either of the two methods above and will turn his head towards the plate and use saccadic eye movements to find the ball. Where the batter looks will be based on his calculation on the flight of the ball. This calculation will include an estimate of how much the ball should drop because of gravity and how much other pitches they have seen have moved. If the calculation is wrong, the batter may swing over or under the pitch. 

Spin and speed are the two crucial elements that determine how much lift will be on the ball. A four-seam fastball is more likely to have great spin and speed and tends to have a spin axis more parallel to the ground. 

A batter using saccadic eye movement to locate the ball crossing home plate would be far more likely to guess low on a four-seam fastball. To them, it would seem like it “rose” and defied gravity. 

My guess, Tom Seaver, at the plate, was the third type of batter. He saw batters swinging under his fastball and assumed it was rising.

The rising fastball is not a myth, but an optical illusion created by a mixture of physics, your eyes, and your brains. 

I also think there is a lot more eye movements can tell us about baseball. The more pitches you see in a game, the more your mind will remember and help in predicting the flight of the ball. Based on the strategy one uses with eye movements there are different strategies pitchers take to exploit a batter’s natural tendencies.

But, in the end, just enjoy your rising fastball regardless if you want to think they are gravity-defying or optical illusions.