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The Physics of the Knuckleball
snoop.daub writes "R.A. Dickey, pitcher for the New York Mets, has been in the news this week after two dominant pitching performances in a row, holding opponents to one hit in each of the games for the first time since Dave Stieb did it in 1988. He has taken over as the league's only knuckleball pitcher after Tim Wakefield retired last season. But just what is it about the knuckleball that makes it hard to hit? Conventional wisdom has it that the lack of spin on the knuckleball causes it to move in completely unpredictable ways, even changing directions in mid-flight. In the last few years, there has been a lot of good science done to understand baseball pitch trajectories, and a few months ago Prof. Alan M. Nathan showed that knuckleballs aren't really so different from other pitches. It turns out that the same 9-parameter equation that can be used to describe other pitch trajectories applies just as well to the knuckleball. The difference appears to be that, like in a chaotic system, knuckleballs depend sensitively on the initial conditions, so that small changes can cause randomly different forces at the start of the pitch which determine the resultant trajectory. Much of this and similar work depends on the Pitchf/x tool, which has recorded the complete trajectory, spin angle and spin rate of every MLB pitch since 2007! Baseball really does have the best sports stats geeks."
Also the reason why a good change-up can be effective; looks like a fastball, moves 10-20 MPH slower.
That's because if you took the stats out of baseball, there'd be nothing left.
Actually, that's not what he said:
So, what has this analysis taught me? For an ordinary pitch, the trajectory follows a smoothly curving line approximated by nearly constant acceleration. For a knuckleball, rather than a line, imagine that the trajectory is confined to lie inside a tube which itself follows a smooth curve. However, the ball is otherwise free to flutter and zig-zag within the confines of the tube. With that picture in mind, the analysis I have presented shows that the diameter of that tube is very small, on the order of a few tenths of an inch at most.
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The smoothness conclusion appears to contradict the popular belief that knuckleball trajectories are erratic and often experience abrupt changes of direction. Let me speculate that this belief is the result of the randomness of movement, both in magnitude and direction, giving rise to the perception of erratic behavior. We have all seen instances where the catcher and pitcher get their signals crossed, and the catcher has to lunge for the ball at the last moment. The catcher expects a certain movement, and the pitcher throws something with different movement. With the knuckleball, no one really knows what movement to expect, so it is not surprising that the catcher has some difficulty cleanly catching the ball and that the batter has even more difficulty hitting it.
make imaginary.friends COUNT=100 VISIBLE=false
It's nice to see the pracitioner of a fine skill be successful where traditionally the best pitcher is the one who can throw the fastest (under control of course).
A similar scenario happens in cricker where a great spin bowler can dismantle a team. Until the 1990's bowling in cricket was dominated by extreme speed where the best bowlers could bowl at over 150 Km/Hr. Along comes Shane Warne, considered the 2nd most influential cricketer in the 20th century who bowls at less than 100 Km/Hr but with a wicked spin and fantastic control.
Check out the "Gatting ball" video below for a delivery of pure beauty.
http://www.youtube.com/watch?v=rOVei8iTyM8
It was Warne's first Test Match delivery in England!
I'm sure it's the same in baseball. Batters don't have time to judge the ball's trajectory itself so they rely on the pitcher's delivery to tell them where the pitch is going. When a knuckleball comes their way, there's nothing to read because even the pitcher doesn't know where it's going.
You're close, but not quite right. Batters can pick up some aspects of the pitch from the delivery, especially at lower levels of play, but pitchers try very hard to avoid "tipping their pitches" in such a manner. So in the majors, what batters really look for is the spin of the pitch, judged by looking at the conveniently bright red seamsw. Since major league pitchers throw balls with 2000+ RPM of spin on them, the seams will mostly be a blur, except for key exceptions. For example a 2-seam fastball will appear to have two pinkish vertical stripes on it. On a sinker, those stripes will be tilted. Breaking balls look like they have dots (as the axis of rotation passes through or near the seam), with the dots in different places depending on the type of pitch. Of course, you only have about 200 ms to pick up the seams. On a 3" diameter circle. From fifty feet away. That sharp vision and quick thinking is probably the number one element in setting apart top hitters.
On knuckleballs, there's nothing to read. Which means that major league hitters need to forget about their standard approach. All their skills and practice count for nothing, and they're forced to just hack away at it the way you or I would (albeit with a swing that won't draw laughter from the crowd).