The knuckleball is really a truly awesome pitch. It looks slow enough for you and me to hit it, but it still baffles major league hitters. It evens baffles the catcher behind the plate who has to try and catch the pitch, resulting in a whole lot of wild pitches and passed balls!
But how does it do this?
(Before I begin, I want to give credit to Dan Brooks who inspired this article with a similar article on Tim Wakefield's knuckleball he wrote about 2 years ago. That article used a different graphing technique and doesn't seem to be available right now at Brooks Baseball or I'd link it.)
Take a look at the following graph. It shows the pitch tracks (the paths of each pitch) of four random knuckleballs thrown by R.A. Dickey this year up to a quarter of a second after the pitch has left Dickey's hand.
Figure 1: The Pitch tracks of four knuckleballs thrown by R.A. Dickey this year up to where they were when the pitches had traveled for .250 seconds. Each Color represents a different pitch on it's way to home plate.
A typical knuckler takes half of a second (.5 seconds) to reach home plate, so these pitches are about halfway between the mound and home plate. This is also around the point in time when a batter has to decide whether or not he'll be swinging at these pitches.
Now, if you're a batter and this is what you've seen on these pitches as they are halfway to the plate, should you swing? Where are the pitches going to end up? The yellow and dark blue pitches look to be going in the same location toward the middle of the plate (the black box). The dark green and light blue ones seem to be curving but how far will they go? Will they end up in the strike zone?
Let's find out. Below, are the actual results of these pitches.
Figure 2: The Completed Pitch Tracks of the above pitches.
As we can see, these pitches certainly moved a lot from when we last saw them. The yellow and dark blue pitches looked the same, but the yellow pitch darted downwards and in on a righty batter (it resulted in a swing and miss) until it hit the corner. The dark blue pitch instead stayed mostly straight and hit the middle of the zone (for a called strike). The light blue pitch hooked and completely reversed its original direction and then dove into the dirt, while the green pitch hooked toward the middle of the plate and hit the dirt.
Four of the same type of pitch and each moved in a totally different way. That's why it's hard for a batter or catcher to keep up with the pitch: because it's nearly impossible to predict how a knuckleball of Dickey's will move and the pitch's movement only becomes apparent after a batter has decided whether or not to swing.
Oh, and before you go thinking that those four pitch tracks above are the only way the knuckler can move, well, the chart below ought to change your mind:
Figure 3: A Plot of the movement of all of R.A. Dickey's pitches this year. Red pitches are the fastballs. Blue pitches are Dickey's Knuckleballs. The chart is from the catcher's point of view, so the more left a dot, the more inside that pitch is on a right-handed batter.
As you can see from the huge spread of his knuckleballs on the above chart, the pitch can literally move ridiculously far inside or completely the other direction. There's one knuckleball recorded as having moved 15 inches away from a left-handed batter and there's one knuckleball that moved 13 inches toward a left-handed batter. Similarly, knuckleballs have regularly dropped around eight inches more than a pitch is expected to due to gravity, but other knuckleballs have risen five inches more than we'd expect.
Clearly this is one unpredictable beast of a pitch. Let's just hope it's unpredictability doesn't come back to hurt us very often.