Understanding the consequences of spin on the baseball


Two things. First, I wrote the attached piece about spin to try to clear up some misconceptions. For instance, a sinker is actually just a ball with less backspin than a fastball. I’d appreciate feedback. Second, I believe that the two-seam fastball has different action from the four-seam fastball because the pitcher gives it some horizontal spin and less backspin. The actual two-seam vs. four-seam difference is of less consequence. Agree?


It is interesting and fun to mess with grips in an effort to get different movement.
What I really want to see is an accurate way to measure ball break…just not size of break but when pitches are breaking in relation to the plate. I know some are doing studies with spin rate in an effort to understand this among other things.


It seems like the basics of it are increase of backspin equals reduction in drop and increase in forward rotation adds to the drop. Increases in horizontal rotation reduce drop and increase run. At a fixed distance (60’6"), increases in velocity, within a given range, generally delay the start of the movement and increase the rate of movement.

The longer a pitch behaves like a fastball, the more effective it can be. That’s why a slow curve with two feet of break is easier to hit than a fast curve with 6 inches of break. If the break is late enough, it really only needs to move a small amount to cause an off-center hit and 3 inches of break can result in a total miss.


Thanks, Coach Paul. This is what I don’t fully understand: “increases in velocity, within a given range, generally delay the start of the movement.” Why would that be? I wonder if, instead, the rate of horizontal movement stays the same throughout the pitch, but the angle becomes more perpendicular to the batter as the ball travels through its arc. That would give the appearance of late break. Did you see the late break optical illusion I linked to? Maybe it’s just that. Late break is a mystery to me. I don’t understand the physics involved.


Late break isn’t an optical illusion it’s physics. Three forces on a pitched ball; gravity, the force from the pitch the projecting it forward, and air. Gravity of coarse makes it go down. The air slows it down and is what moves it with different spins giving it different movement from air flow. Last the force behind the ball. As long as it is greater, it reduces the impact of the other two. Since its force production stops the moment the hand is removed. It’s force dissipates and the other two forces impact the ball more.

Imagine a bowler. The ball doesn’t curve the entire bowl. At first it travels strait until the force projecting it away from the bowler dissipates enough that the force of friction moves the ball. Same thing just differnt forces.

Same as a draw or fade in golf. Not to be confused with a slice or hook which can in fact be curving the entire time. As such in the case, of when I hit a golf ball lol.


I’m not sure if the bowling ball analogy works. The forward movement of the baseball is key to the Magnus force that bends the trajectory of the baseball. I’m not sure if a bowling ball curves for the same reason. (The spinning motion grips the ground and creates horizontal movement irrespective of forward movement, I think.) It may even be that a slower forward motion of the ball creates less Magnus force. Bob Gibson implies this in his new (excellent) book “Pitch by Pitch.” Gobson calls a “backup slider” a slider with too much side spin and not enough forward speed. According to him, it is thus pretty straight, which surprises the hitter creating the illusion of a back up.

Re late break as an illusion, check this out: http://www.moillusions.com/secret-of-curve-ball/. It doesn’t mean that a curve ball doesn’t curve – it certainly does – but it does show that the eye will perceive lateral movement when a spinning objection moves from peripheral vision to normal vision, as a baseball does when it gets closer to the batter…


faster pitch = later break
However, if you throw hard enough, the break can be so late that it doesn’t have a chance to move enough to throw the hitter off the mark.
Mostly, it’s gravity and air pressure being constant that increases the break. As the velocity drops, gravity, air pressure, and the rotation take over.


Interesting topic here. Does anyone know how to maximize the spin on the baseball?


Well, the thing to keep in mind is what you are trying to accomplish.
The less the spin rate on a fastball or change the more it sinks. The more the spin rate on breaking balls the sharper the break. So, if you want a change with a good sink you would want less spin…you want a curveball with sharp break, you want more spin.
The ability to spin the ball more or less depending on the pitch? I haven’t seen anyone be able to teach this…or really reliably measure it. I know there are people working on this.


Maximize your spin rate by getting your release point out front. This article explains how a release point that is out front creates better spin and increases “perceived velocity” and that both of these result in greater success:

Two caveats…

  1. The article uses the term “effective velocity” to describe batter reaction time in terms of velocity and distance but “perceived velocity” is, I believe, the more common term while “effective velocity” is more commonly used to describe Perry Husband’s concept involving “perceived velocity” plus the effect of location.

  2. The article uses the term “extension” to refer to getting the release point out front. “Extension”, I believe, is commonly interpreted to mean reaching with the throwing arm but that is NOT how you get your release point out front.


Pretty cool info there. But how would you get your release point out in front? Longer stride?


Release point location along with stride length are a result of other things that happen earlier in the delivery. Do those other things well and let release point and stride length happen. “Those other things” include:

  • Maintain a stable posture into foot plant and release
  • Take care of the glove side to stay closed and rotate late
  • Create significant early momentum