Two Seamers

[pobguy]

(The other problem is that the PITCHf/x systems spin calculations seem to be off quite a bit.)

The spin calculation..that is, the rate of spin (RPM)..that PITCHf/x reports is just an estimate, based on the amount of movement that is measured. The estimate is based on laboratory experiments that relate movement to spin rate. Those experiments are hard to do with great precision (I know because I did one of the myself!). As a result, our knowledge of the quantitative relationship between spin rate and movement is rather imperfect (perhaps known to about +/- 20%).

When you say that the PITCHf/x spin seems to be way off, I would ask *relative to what?* Perhaps you mean the Trackman radar system, which is able to measure the spin and which will be installed in every MLB ballpark for the 2015 season. Or perhaps you mean high-speed video, but we really don't have much of that to compare with PITCHf/x. Just curious about the basis for your statement (which, as I have said, I don't dispute).

 

[colin]

could wind speed and direction account for that 20%?

 

[BuckeyeGuy]

So are they the same or similar? A 4S traditional curve is similar to a 2S cutter. To one degree or another all pitches are similar, granted some more than others.

Movement as in cutting in or out, not the overall pitch.

FWIW, just by holding a ball and turning it in my hands I think that the movement of the pitches have to be similar, but I would expect the 2S to move a lot more (relatively speaking). The amount of yaw is absolutely key from what I see - too much or too little and you pull the seams too far out of the air flow to create a useful pressure gradient.

I can't even begin to do the math, but I think the motion is a the result of a combination of the Magnus effect and Bernoulli's principal. This is straight intuition.

 

[riseball]

Movement as in cutting in or out, not the overall pitch.

FWIW, just by holding a ball and turning it in my hands I think that the movement of the pitches have to be similar, but I would expect the 2S to move a lot more (relatively speaking). The amount of yaw is absolutely key from what I see - too much or too little and you pull the seams too far out of the air flow to create a useful pressure gradient.

I can't even begin to do the math, but I think the motion is a the result of a combination of the Magnus effect and Bernoulli's principal. This is straight intuition.

It is a regular part of the workout to tweak the release (finger pressure) to provide optimal yaw and the grip to optimize the seams. Getting all the parts to play nice is the challenge.

 

[pobguy]

could wind speed and direction account for that 20%?

Not for the laboratory experiments, which are done under climate-controlled conditions. The scatter of the data due to the difficulty of the experiment account for the 20%. Now, in a game situation, the wind speed and direction does affect the movement, so that introduces even more uncertainty to the determination of the spin rate (and also the spin axis). Interesting question.

 

[Rocketech1]

For what it's worth. DD would experiment with a two-seam fastball and there appeared to be less predictability of spin direction versus her 4-seam fastball the had 12-6 spin. For example sometimes the 2S would run in towards a right handed batter and other times run away from a right handed batter. Maybe the placement and pressure of the finger tips had a lot to do with its unpredictability not necessarily its smooth side versus rough side orientation? Nevertheless, she abandoned the 2S and hasn't thrown one for several years now. But it has me thinking I should have her try a 2S now to see if she gets the same results or more predictable movement?

 

[BuckeyeGuy]

For what it's worth. DD would experiment with a two-seam fastball and there appeared to be less predictability of spin direction versus her 4-seam fastball the had 12-6 spin. For example sometimes the 2S would run in towards a right handed batter and other times run away from a right handed batter. Maybe the placement and pressure of the finger tips had a lot to do with its unpredictability not necessarily its smooth side versus rough side orientation? Nevertheless, she abandoned the 2S and hasn't thrown one for several years now. But it has me thinking I should have her try a 2S now to see if she gets the same results or more predictable movement?

I'll bite: Fingertip placement and pressure does what to the pitch, exactly? Do they not change the orientation of the ball at release?

 

[Perfect Circle]

I'll bite: Fingertip placement and pressure does what to the pitch, exactly? Do they not change the orientation of the ball at release?

The bite is it takes 50 pitches a day, 6 days a week for 2 mo. The first finger pressure you learn is to peel it off the middle finger for a 12/6, then you go to the index finger for the 11/5 & or the 1/7... Then its subtraction from there.

EP: See my .gif way back on page 9 for the 12/6

 

[riseball]

I'll bite: Fingertip placement and pressure does what to the pitch, exactly? Do they not change the orientation of the ball at release?

The placement of the fingertips and pressure determines the last finger off the ball which influences the geometry of the pitch. The grip determines the orientation of the seams within that geometry. Experiment with the pressure until you get the desired geometry then adjust the grip to get the most movement.

 

[JJsqueeze]

The placement of the fingertips and pressure determines the last finger off the ball which influences the geometry of the pitch. The grip determines the orientation of the seams within that geometry. Experiment with the pressure until you get the desired geometry then adjust the grip to get the most movement.

This is all there is to finger pressure. Important but no real magic, just giving a pitcher a mechanism for making sure the finger they want to dominati spin is consistently the last thing to act on the ball.