THE BOOK--Playing The Percentages In Baseball

This is a battle I don’t think you’ll ever win, Tom.  In some senses, you’re right that there are practical differences between a Jamie Moyer fastball and a Randy Johnson fastball, but for pitchers, the understanding of a pitch type is based on grip, not on what the ball does after it moves. 

Randy Johnson and Jamie Moyer both grip their four seam fastballs the same way.  Before they begin their windup, the two pitches are indeed the same.  The difference between the results of the pitch is a physical difference between the individuals involved, not in the process of the pitch being delivered.

I probably conflated two things into one. I was trying to refer to spin upon release.  If they both impart the same spin rotation (direction and rate, like rpm, or rps), then I’m ok with calling a Moyer and RJ fastball the same pitch (as long as their fastball also includes the speed upon release).

My issue is with all the current pitch tracking heavyweights that try to use “gravity-less” numbers with normal english words.  Certainly, no one talks about these things, other than physicists.

But if you were to say that Moyer’s fastball is thrown at 12 rotations per second, with topspin with the thumb leading through at NorthWest, or WestNorthWest, released at three-quarters, that would certainly be more meaningful. 

I simply don’t like seeing the word “movement” in any of these articles, since it’s not a movement that is being described, but the part of the movement that is attributed to spin, over and above the movement that gravity is responsible for.  For this to have any meaning, you’d have to know how much gravity affects things on a spinless (likely stitchless, to exclude knucklers) ball.

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You bring up another good point, one which I don’t think any of us talk about.  I always talk about:
speed,
spin rotation and direction,
release point and direction

But, grip would also be important.  You can thrown two pitches with the same speed, spin, and release, but if you grip one pitch on the seams and the other cross-seam, the movement of the pitch will be different. 

So, while we should be able to note the location of a pitch based on the three (really 5) parameters I noted above, the actual location of the pitch, different from the estimate, should tell us how the pitch was gripped.

Have I missed some of the discussions on this?  That is, the 4the variable required is: grip.

Tango wrote:

I also think we’re going to be at the point that it doesn’t make sense to call his pitches “fastballs”.  A Jamie Moyer fastball would be a Randy Johnson changeup.  I would much prefer a nomenclature based on all pitchers, rather than to himself.  The nomenclature of the pitch can probably be represented by the spin of the ball.  So, you can have a 87 mph fastball and a 98 mph fastball, if we agree that a fastball is thrown with a certain amount and direction of spin.  So, the “movement” (i.e. spin) numbers that John is showing is what decides what kind of pitch is thrown, irrespective of the speed.  The speed is simply a qualifier to the spin of the pitch.

I sort of agree with the spirit of this, but I’m not sure it would actually be a step forward. Consider two Hernandez’s: Felix’s change-up has very similar movement to Livan’s fastball and is actually thrown 2-3 mph harder. But, they really shouldn’t be called the same pitch, because batter reaction to the two pitches will be very different. 

The way a batter reacts to a pitch depends a lot on what he is expecting and that very much depends on who is pitching. The standard names like fastball, change-up, etc., help to remind us of that.

Also, I would not relegate speed to a qualifier to the movement parameters (including gravity, if you like), to classify pitches in a pitcher-independent system. Speed is probably the most important parameter of a pitch (along with its location). Anyway, it might be interesting to divide the movement plot into a few zones (like 6) and make 6 speed buckets—that’d give you 36 different “pitches”, although I bet only about half of them would be thrown with any frequency. Oh, there’s another reason for naming pitches with the standard names—we only need to know about 5 or 6 pitches, instead of 15 or 20.

My issue is with all the current pitch tracking heavyweights that try to use “gravity-less” numbers with normal english words.  Certainly, no one talks about these things, other than physicists.

I tried submitting to THT an article that contained only integral signs and Greek letters, but they haven’t seen fit to publish it yet [g]

Actually, I’m still rather agnostic on this issue—I realize that the movement variables I use are perhaps non-intuitive to many, but they have advantages over the alternatives (e.g. they are uncorrelated). By the way, for horizontal movement, there is no confusion, since that is what is really being displayed (i.e. gravity has no effect). I’ve played around with including the gravity part of the vertical movement, but haven’t been satisfied with the results. 

Regarding grip, those are good points. I think a good subject for study with pitch-f/x is the 2-seam vs. the 4-seam fastball. I think there is a lot of anecdotal evidence regarding the differences (2-seamer is said to sink more and be slower), but I’m not sure about hard evidence. I have read of lab tests that refuted the notion that a 2-seamer will not go as fast as a 4-seamer. This seems like something that pitch-f/x could shed some light on.

As for “grip” being the 4th variable, the word “grip” is often meant to indicate the position of the fingers on the ball (fastball vs. split) and not just the orientation of the seams.  To specify the “grip” in your sense, you would have to specify the orientation of the ball (defined by the position of the stitches) with respect to the spin axis.

There are probably 2 reasons why this isn’t discussed much (aside from comments on 2- and 4-seam fasetballs): it’s usually a small effect compared to the other variables, especially for non-fastball pitches. The other reason why we don’t talk about stitch orientation much is that we don’t have any data on it—obviously it’s not part of pitch-f/x—although, I’d love to have info whether any given fastball was throw with or across the seams.