How to Legally Scuff a Baseball: Post 45

Scuffing a baseball is effective as heck at getting some additional break on your pitch. As shown in our Post 44, and as every experienced pitcher seems to know, the ball moves away from the scuffed side. It breaks quite a lot, as it turns out.

But, that is not actionable, as they say. Doctoring the ball is so against the rules that even the Astros don’t do it (sorry, I had to pile on).

BUT, you can make a baseball act like it is scuffed. The trick is to cause a seam to reside on one “pole” of the ball. By pole, I mean the point where the spin axis protrudes from the ball. In the video below, the pole with the seam would be where my middle finger is on the ball. The spin axis does not matter, so this will work on any pitch with a lot of active spin (high efficiency). It only requires that the pole of the ball be at a point 90 degrees from the ball direction and the fattest part of the ball.

If that doesn’t make senes, just think about a 12:00 fastball with all active spin (100% efficient). If you wanted to throw that pitch and make a scuff on the right, it would look like this from the pitcher’s point of view. Note that there is a seam always present on the “pole” of the right side.

So, even though we gave Rickey Norton back his Rapsodo, we asked to borrow it one more time and test this idea. We also had to convince Terry Zollinger to let us set up in his machine shop one more time. In order to cause the ball to have a seam on the pole of one side of the ball (and not on the other side) it was loaded into the flex tip as shown below. Remember that the tip spins the ball because the top is sticky while the bottom is slick.

John Garrett and I took the data yesterday. I was mostly there to return the ball which must be carefully tossed back to the cannon operator (John) without leading him into the pit of death.

From the Rapsodo iPad it looks like this:

This test used a brand new 2019 MLB baseball. The average speed was around 90 mph and the balls spun at 12:00 at about 1100-1200 RPM. The movie camera sees this, one each for the different orientations, which should be visible in the first few frames. These are formatted for iPhone. If you’d like a hi-res version, just message me.

“Scuff” on left
“Scuff” on right

Data were acquired as such: 2 4-seam, 2 SL, 2 SR, then start again with the 4-seam. This was an attempt to prevent bias due to wear on the ball during the test. We shot 9 total in each orientation.

The results are shown in the plot below. The 4-seam is used as the baseline, so its mean is 0,0.

Pitch locations. Each pitch was repeated 9 times and the average of these is indicated with a cross hair.

Although we do not get as much action as an actual scuff, we get a similar effect. The ball moves away from the scuff. For reasons we do not understand yet, we were not able to get as much effect from the right side. This is likely a failure to align the ball properly in the tip.

When the scuff works, note that the ball arrives lower in addition to breaking right. This is consistent with the scuff generating a massive boundary layer separation on that side of the ball, which will increase drag and slow the ball a bit.

A quick note about the Rapsodo data and what it makes of this sort of pitch. Recall that Rapsodo 1.0 measures the ball spin and location directly in the last 20 feet. It then attempts to determine where the ball came from by applying a Magnus model.

In the data below, CT refers to Scuff Left, OT is Scuff Right, and FB is the 4-seamer. Note the consistent shift in the release parameters for the different pitches and that they are all spinning the same and have the same speed.

A reader asked me how to grip this for a fastball, and I made this explanation:

So, pitchers: you can add more than 4 inches of break to any active-spin pitch simply by aligning the ball in your hand properly. We didn’t show it as well as I’d hoped, but there is no reason you could not bend it just as much to the other side by switching which pole has the seam. If anyone is able to pull this off, please let us know!

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6 thoughts on “How to Legally Scuff a Baseball: Post 45

  1. What about wobble? Spin rate is one thing , but there is also a degree of wobble which will affect pitch as it reaches a certain point with regard to velocity and release point, angle of declination, etc.
    No one seems to address this wobble factor. Does it not factor?

  2. I have pitched and coached at a competitive amateur level for a long time with some success, and I always attributed the very late break on the 2 seam sinker…arm side fade that breaks just in front of the plate due to the wobble causing the spinning seam to reach the optimal place in time and space to catch the air and create a greater affect to the late break on the pitch.
    Of course this is just a theory, but I remember as a kid playing with spinning tops, and later with footballs and frisbees, that a spiral reacted differently from a wobbler, even though they were both spinning in the frontal plane, but wobbling in the transverse plane or lateral planes.
    Does that make any sense?

    1. Sure. My point is just that one of many ways that our pitch measurements are simplified is that measurement systems all assume the spin axis and rate is constant. I know Diamond Kinetics is aware that this is not true and are interested in learning about it through their Smart Ball.

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