Like Eating Jell-O With Chop-Sticks: Analysis of Knuckleball Pitchers

Published by on November 8, 2020

“Not only can pitchers not control it, hitters can’t hit it, catchers can’t catch it, coaches can’t coach it and most pitchers can’t learn it” –American League umpire Ron Luciano (Freier, 2012)

Baseball may be boring to some, but it is a romantic game to those who play it. None would agree more than knuckleball pitchers, those who can only hope to explain their craft through analogies.

Major League Baseball (MLB) veteran Wilver “Pops” Stargell once said, “Throwing a knuckleball for a strike is like throwing a butterfly with hiccups across the street into your neighbour’s mailbox” (Freier, 2012). Simply stated, it is extraordinarily difficult to throw a knuckleball to strike opposing batters out.

“So why throw a knuckleball”?

This is a reasonable question to pose if one has never witnessed the tangible chaos to which the opposing batter is subjected. Throughout the storied history of baseball, batters have described attempts to hit the pitch in an almost infinite number of ways; a direct reflection of the ways in which it buckles knees and turns batters into dancers. A handful of my personal favourite descriptions include:

“It comes up, makes a face at you and then runs away” -Jackie Robinson (Freier, 2012)

“Like trying to eat Jello-O with chop-sticks” –Bobby Murcer (Freier, 2012)

“Trying to hit a knuckleball is akin to swatting a fly with a blade of grass” -Pat Jordan (Freier, 2012)

The knuckleball pitch may appear as supernatural to observers; but it, like any other pitch, can be explained using aerodynamics (Morrissey, 2009; Watts and Sawyer, 1974). There are a multitude of other pitches in baseball, such as the fastball, slider and curveball, that are used by the majority of MLB pitchers. These pitches vary in the way they are thrown by the pitcher. The fundamental points that alter how a baseball is thrown are the axis of rotation, speed, orientation of the ball, direction, and magnitude of angular velocity (Morrissey, 2009; Watts and Sawyer, 1974). Take, for instance, that a two-seam and four-seam fastball have exactly the same velocity, axis of rotation, and angular velocity but differ in orientation. The result is that the two-seam fastball develops slight movement (both horizontally and vertically) while travelling towards the plate, whereas the four-seamer travels straight. The knuckleball is an oddity in that it can be pitched the same way each time and yet never move the same way twice (Morrissey, 2009).

For those unfamiliar with baseballs, the general elements of the ball’s surface that factor into pitching-grips (orientation) are demonstrated in the figure below:

Figure 1: The general regions of a baseball associated with pitcher grips in order to create variation in pitch behaviours (Morrissey, 2009)

Former Toronto Blue Jay R.A. Dickey remains the only knuckleball pitcher to win a Cy Young award (2012), awarded to the best pitcher in baseball. R.A. gripped the ball with his fingernails placed behind the seams in the horseshoe region making an inverted “V-shape” with his pointer and middle fingers (Figure 2). This enables a very slight amount of torque to be applied to the baseball, which makes it rotate forwards (the top of the baseball rotating towards the catcher), with the axis of rotation to be horizontal in Figure 1 (Morrissey, 2009; Johnson, 2016; Cross, 2020). The pitch can therefore be considered a “two-seamer”, but is thrown much slower than a fastball (65–82 mph vs. 90–100 mph).

Figure 2: Former Blue Jays ace pitcher R.A. Dickey shows off his knuckleball grip (Davidson, 2013)

In interviews, R.A. Dickey stated that an ideal knuckleball involves rotating the baseball so that the seams cross the front of the ball. Conversely, if this does not occur, the landing strip (Figure 1) will be left exposed, rendering the pitch stagnant and an easy homerun, because the seams will not induce the necessary lift-force (Morrissey, 2009; Cross 2020).

As shown in Figure 3 below, the greatest difference in lift was between 120–300° rotation as the knuckleball was thrown. Through analysis of the lift force during the flight of the pitch, a batter would observe that the baseball does not drop much initially, before dramatically dropping halfway to home plate. Most notably however, as the baseball approaches home plate, the severity of the drop decreases, which changes the slope of lift. This effectively fools opposing batters into swinging in the wrong place (Morrissey, 2009).

Figure 3: Observed forces exhibited by a knuckleball at varying orientations (0°-300°)(Morrissey, 2009). The balls represent the orientation of the knuckleball from when it leaves the pitchers hand (left) to when it arrives at home plate (right).

The highest standard deviation of lift force exhibited by a knuckleball is observed at 120° (Figure 4). This directly accounts for the unpredictability of the pitch, because the initial lift experienced by the baseball differs each time, making it rare for a batter to face the exact same pitch again (Morrissey, 2009; Whobrey, 2011).

Figure 4: Standard deviations of lift force (lbs) of a knuckleball at all orientations in a wind tunnel. The lift forces exerted on the knuckleball (still) varies much more than that of a spinning pitch, which helps account for the pitches’ unpredictability (Morrissey, 2009).

To conclude, a proper knuckleball is extremely difficult to hit, even with extensive knowledge of the related aerodynamics and physics. This is because the knuckleball is an exemplar of the term “Chaotic Dynamics” (Whobrey, 2011): simply summarized, small changes in the initial conditions of a system (spin rate) result in large alterations of the outcome (location of ball at home plate).

References:

Cross, R., 2020. KNUCKLEBALLS. [online] The Physics of Baseball. Available at: <http://www.physics.usyd.edu.au/~cross/KNUCKLEBALLS.htm> [Accessed 8 Nov. 2020].

Davidson, N., 2013. Knuckleballer R.A. Dickey casts unique shadow at Toronto Blue Jays camp | Times Colonist. [online] Times Colonist. Available at: <https://www.timescolonist.com/sports/baseball/knuckleballer-r-a-dickey-casts-unique-shadow-at-toronto-blue-jays-camp-1.79662> [Accessed 8 Nov. 2020].

Freier, J., 2012. The Top 5: Knuckleball Quotes. [online] SB Nation New York. Available at: <https://newyork.sbnation.com/new-york-mets/2012/7/3/3134637/the-top-5-knuckleball-quotes-ra-dickey-bob-uecker-jim-bouton-willie-stargell-jason-varitek> [Accessed 8 Nov. 2020].

Johnson, R.A., 2016. The Knuckleball Club: The Extraordinary Men Who Mastered Baseball’s Most Difficult Pitch. Rowman & Littlefield.

Morrissey, M.P., 2009. The Aerodynamics of the Knuckleball Pitch: An Experimental Investigation into the Effects that the Seam and Slow Rotation have on a Baseball. p.184.

Watts, R.G. and Sawyer, E., 1975. Aerodynamics of a knuckleball. American Journal of Physics, 43(11), pp.960–963.

Whobrey, D., 2011. Dickey’s Nasty Knuckleball. [online] Available at: <http://baseball.physics.illinois.edu/DickeyPitch103a.html> [Accessed 8 Nov. 2020].