The Pitching Mechanics of Throwing Strikes

In my previous article on control problems, I talked about the kinesiological factors that can go into wildness and command issues. In this post, we’ll talk about the specific mechanical factors that go into throwing strikes – with a heavy emphasis on the actual component of physics and mechanics, rather than standard coach-speak of acquiring a target and other mental factors which have been repeated ad nauseam on the Internet in an effort to gain easy pageviews.

“Just stare at the target intently!”

Not exactly. Let’s get into the particulars.

Actual Margin of Error

At the risk of stating information that everyone knows, here’s a nice layout of a baseball field with all the relevant dimensions:

We will also assume the pitcher will release the ball 55 feet away from home plate. This number was chosen because Dan Brooks and Harry Pavlidis use it on their great PITCHf/x tool, and insist it carries greater realism than using the Gameday/MLBAM standard of 50 feet. Good enough for me.

A lot goes into throwing a baseball at a specific target, of course. Here are some of the factors that we won’t focus on:

• Spin rate
• Release velocity
• Angle of spin
• Barometric pressure and relative humidity
• etc, etc

You get the idea. However, what I don’t think is appreciated enough is the fact that huge misses at home plate can happen on very small adjustments at release.

Let’s assume your release point only varies in initial trajectory by 1° (approximately 0.01745 radians) in all directions. Therefore, assuming a 55 foot radius, the length of 1 arc is angle * radians, or in this case ~0.96 feet in each direction.

(We’ll use a circle here for simplification, but the number is actually larger since we are throwing a projectile against a “flat” surface of the front edge of the strike zone and therefore has greater depth as you move away from the origin point – but we’ll keep it as basic as possible.)

The size of the strike zone varies based on the hitter’s height, umpire in question, and even the count! However, in a general sense, the strike zone is about 1.8 feet tall and 1.5 feet wide giving the pitcher the slight benefit of the doubt. That means if you have a perfect 1° tolerance in any direction, a ball meant to be thrown middle-middle that splits the strike zone in perfect quadrants misses the target slightly high/low at the ends of the margins (0.96 feet * 2 directions = 1.92 feet tolerance high/low vs. 1.8 foot zone) and wide at the ends of the margins by quite a bit (1.92 feet tolerance left/right vs. 1.5 foot zone).

However, consider that the strike zone expands diagonally (Pythagorean Theorem and all) and you have additional tolerance for missing to the corners – certainly a relief there!

And that’s assuming you can control the tolerance of your release point by a measly 1° in each direction! How little is 1°? Try this right now – hold your pitching hand up with your palm facing the floor. Rotate your hand so the thumb is pointing in the opposite direction (to the right for a RHP, to the left for an LHP). OK. That’s 180° of motion. Do you think you can consciously move your hand by 1/180 of that distance some 100+ times per game?

How Does ANYONE Throw Strikes?

Actually, this is a good question, since if you did the exercise above, it should throw doubt in your mind on how you can even control your release point within 5° of tolerance – much less 1° of tolerance!

The answer is definitely NOT coaches yelling at you to change your mechanics on the mound during a game – or for you to even think that way yourself. You have already demonstrated to yourself that you cannot adequately isolate 1° of forearm rotation, to say nothing of controlling the angles of your spine, torso rotation, internal rotation, and so many other kinematic variables that go into throwing a ball! So don’t think about your “mechanics” when you’re wild.

Proprioception is the correct answer. It is often called “feel” or “sense” by coaches and analysts, but it’s far more complex than that. Proprioception is not a conscious act – it is a map of your muscles, tendons, ligaments, bones, and nerves that has been built up over hundreds of thousands of reps of throwing objects or similar patterns that integrate themselves into this neural net of human action. Ever wonder why a 9 year old can’t hit the broad side of a barn? Yes, the young athlete is skeletally immature, but he is also lacking the proprioception that unconsciously guides his arm into the proper places to throw a strike to the target.

This phenomenon is also responsible for relatively inefficient pitching mechanics that all humans display. In Feltner and Dapena’s groundbreaking work on the biomechanics of throwing a baseball, they proposed a more effective model of throwing a baseball at higher velocities:

However, as Feltner and Dapena also theorized:

After stopping the external rotation, the pitcher could conceivably keep the arm in its position of maximum external rotation and simply increase the speed of elbow extension to give the ball a large velocity at release. However, the actual pattern of motion is somewhat different from this (Figures 12 and 13): the arm undergoes a rapid motion of internal rotation immediately after reaching its position of maximum external rotation (Figure 9) , and the elbow stops short of full extension (Figure 10a). The motion of internal rotation may be unavoidable, due to the stretch of the internal rotation musculature and the inability of the abduction and horizontal adduction torques to elicit much external rotation when the arm is nearly straight. Still, regardless of whether the motion of internal rotation is voluntary or involuntary, the combination of this motion with a slowing down of the elbow extension may protect the elbow against injury.

If the elbow joint reached a maximum speed of extension just prior to the instant of full extension, this would lead to a large ball speed, but it would also risk injury to the posterior part of the elbow joint when the elbow locked straight immediately afterward (Figure 19a). The risk of injury would force the pitcher to limit the speed of the ball prior to release. The pattern actually used by the pitchers may be a good solution to this problem: by stopping the extension of the elbow before the attainment of full extension, and combining this with a rapid internal rotation at the shoulder joint (Figures 12 and 19b) , injury of the posterior part of the elbow joint can be avoided while permitting the hand to move forward beyond the position of the elbow without slowing down.

They were ahead of their time – later studies showed that premature elbow extension and the “locking” of the elbow were indeed correlated with increased rate of elbow injuries. The human body (usually) knows this is the case, so this theoretical model is never seen in the wild – though some pitchers occasionally display flaws that come close to this model, no doubt. (JJ Putz is a good recent example.)

Plotting the Map to Improve Control

The above information is interesting, but not necessarily immediately useful. Our theories at Driveline Baseball are to reject the idea of conscious mechanical reformation (except in cases of severe injury to the pitching arm and on a post-throwing program), and to use ballistic tools to help create a better and more detailed “map” for the nervous system to use. Our three-step plan is as follows:

• Getting and keeping pitchers healthy as best as possible so there are few, if any, misfirings due to pain/discomfort
• Developing a more specific and clearer proprioceptive map through weighted implement training (wrist weights, weighted balls, Plyo Ball ®, etc)
• Cataloging and reinforcing mechanical changes through the use of high-speed video from multiple angles

This is our plan of attack in our Pitching Program – and one that we’re fairly sure isn’t duplicated anywhere else!