Comments on: MLB and Umpires reach agreement

By: Noel

Noel — Sun, 26 Dec 2004 09:08:02 +0000

Hey Colm, good point, baseball isn’t a matter of life or death.

It’s far more serious than that.

But actually I did have a good Christmas – excellent dinner with friends (unfortunately the family’s on the other side of the globe) – and hopefully you and all the other USSM contributors enjoyed your Christmas too.

By the way DMZ, you disagreed when I said that a pitch breaks hardest near the end of its flight. Doesn’t it travel on a parabolic path? Sure, the force (gravity) is constant, but the vertical drop increases quadratically.

By: Colm

Colm — Sun, 26 Dec 2004 08:16:02 +0000

Blimey, it’s Christmas Day guys. Lighten up. How come you aren’t too lit up to have such an academic conversation?

By: Noel

Noel — Sun, 26 Dec 2004 06:34:55 +0000

Good point Jose, I shouldn’t have said non-Newtonian; air is pretty close to a Newtonian fluid. And you’re absolutely correct that it’s extremely difficult to calculate the path of the ball in advance – in fact it’s practically impossible. Fortunately, no-one’s trying to do that (I hope); not you, not me, and not Questec.

But you make the same point as I do when you say that “when measuring the path of the ball the calculations become much simpler”. I have no quarrel with the calculations: I’m sure Questec knows how to interpolate. My real question is, how accurate are the *measurements*?

By: Rob McMillin

Rob McMillin — Sun, 26 Dec 2004 03:47:44 +0000

Who MBL is?

By: Shoeless Jose

Shoeless Jose — Sat, 25 Dec 2004 22:27:31 +0000

Aerodynamics are newtonian physics, unless you think there’s some kind of relativistic (fastballs!) or quantum {smallball!) factors to the airflow around the ball. I think what you’re trying to talk about is chaotic (turbulent) flow. This is still newtonian, just not linear. Nonlinear flow is notorious for being computationally intractable. So in theoretical terms, it may be extremely difficult to calculate the path of the ball in advance; however, in practical terms when measuring the actual path of ball the calculations become much simpler. I don’t know enough about Questec to comment on their system, but it certainly is possible and certainly doesn’t require non-newtonian physics.

By: Noel

Noel — Sat, 25 Dec 2004 21:38:22 +0000

Slight typo there – should be “accuracy”, not “accuaracy”.

By: Noel

Noel — Sat, 25 Dec 2004 21:36:47 +0000

Re #14, good point, Dave. In my defence, I’ll note that I was actually not a Christmas baby, so I don’t typically dwell on the Noel/Christmas connection. But a belated happy holidays to all, and good fortune to everyone in the New Year.

Regarding the topic of uneven or discontinuous flight of the ball: Newtonian physics is not the only influence – aerodynamics is also a huge factor, and that can be decidedly non-Newtonian.

Let’s take a more obvious example – the knuckleball. I think everyone agrees that a knuckleball can have absolutely unpredictable “late break” which is mainly due to aerodynamics, not Newtonian physics.

Would Questec be able to accurately track a knuckleball as it approaches the plate?… with an accuaracy of (allegedly) 0.5 inches or better?

It all depends on the frame rate, doesn’t it?… even at a mere 60 mph, the ball could be moving a long way between frames, and the “early” frames at the point of release would be utterly useless for interpolating the flight of the knuckleball near the plate.

If – and I emphasize “if”, because I don’t know, but if the frame rate is only 30 frames per second or thereabouts, then it would be darn difficult for the Questec operator, is all I’m saying. I’m not claiming that Questec is flawed, just that it could be less accurate than they’re claiming, unless they’re using a higher frame rate than normal video cameras.

By: dave paisley

dave paisley — Sat, 25 Dec 2004 17:13:41 +0000

Um, yeah, see Newton, Isaac.

And Noel, with a name like that you coudn’t slip in a Merry Christmas at the end?

By: DMZ

DMZ — Sat, 25 Dec 2004 08:17:25 +0000

Sure, but the ball breaks hardest near the end of its flight, so the data points near the end of the flight (when the ball is near the plate) are much more important than the data points at the beginning (when the ball is just leaving the pitcher’s hand).

That’s…. not true. As it appears to the hitter, the break appears late, but the force on the flight of the ball is constant. See: “Physics of Baseball”, many other sources.

By: Noel

Noel — Sat, 25 Dec 2004 07:26:05 +0000

Sure, but the ball breaks hardest near the end of its flight, so the data points near the end of the flight (when the ball is near the plate) are much more important than the data points at the beginning (when the ball is just leaving the pitcher’s hand).

That’s how it is with interpolation and/or extrapolation: there’s always a particular area of interest, which in this case is the plate. The data points closest to the area of interest are crucial, while the points further away are much less important. In fact, in the case of (for example) a slider with late break, the early data points may even be misleading and counterproductive. Changes in the turbulent airflow over the ball in flight can cause it to develop movement which it didn’t have as it left the pitcher’s hand.

So the more data points that are available *near the area of interest*, the better… which argues in favor of the highest possible frame rate. I’m just sayin’.