The Physics of Baseball

The Physics of Baseball, Adair, 2002

The following summary is condensed from the chapter on The Swing of the Bat:

The process described from the release of a good fastball pitch to the moment the bat crosses the plate takes about 400 milliseconds. For comparison, an eye-blink takes 150 milliseconds. The timing required to begin the swing in time to meet the fastball are as follows:

The initial assembly of the information in the eye takes about 25 milliseconds. The initial information, not really a picture, within the brain from first look at the ball by the batter takes 20 milliseconds. The batter can then fill in additional information stored in his brain (i.e. infield, background) constructs the picture in another 30 milliseconds. So in the time the fastball has travelled nine feet (75 milliseconds), the batter has an initial “picture” to work with. Only then can the batter begin thinking about swinging.

The batter’s brain compares the information with learned and retained patterns from other parts of the brain: think of the choices as a deck of cards that might be shuffled with certain ones on top based on the pitcher’s reputation and the observations from the dugout or on-deck circle. The batter has about 25 milliseconds to select the correct reaction: swing, don’t swing, what kind of swing, or maybe hit-the-deck. The decision is then relayed to the muscles over a 100 millisecond period. The muscles react, depending on the type of muscle, in 10 to 50 milliseconds.
The swing takes about 180 milliseconds, of which the first 30 are shifting the weight to the front foot.

The batter can make significant changes in the first 50 milliseconds of the swing (after the weight shift). In making these modifications, he uses information he gathers by “looking” at the ball for another 50 milliseconds and then “thinking” and “acting” in response to that look. The exceptional athletes who play the game can probably make small adjustments for another 50 milliseconds though at the end of that time the bat is traveling at about three-fourths of its final velocity.

Even if the skilled batter can use this late data, none of the subsequent information from seeing the ball over the last half of its flight can be used at all. If it weren’t psychologically upsetting, the batter could just as well close his eyes after the ball is halfway to the plate or, if it was a night game, management could turn out the lights—the batter would hit the ball just as well. [end of summary]

So, what does that tell me about certain Nationals at the plate?

Some random observations by me, based on the above analysis and game observations:

1. LASIK may help the batter by giving him more accurate data during that first 45 milliseconds, which can then lead to a more accurate “shuffle” of the deck of possible pitches in that crucial 25 milliseconds.

2. The more muscles that are involved in the swing, the more difficult it is physically to send adjusted information to the muscles and adjust the swing once the initial signals have been sent.

3. Experience matters in pitch recognition and response. . . up to a point. At some point, the eye-to-brain-to-muscle reaction time slows down enough that the batter is no longer hitting at a major league level. Changing venues entirely, Jeopardy for Seniors is played separately because no matter how much a slightly older person knows, they cannot hit the button as fast as a younger competitor.

4. Jayson Werth might be right about hitting a major league pitch being the hardest job in the universe. Within that 150 seconds of the swing, if the batter is 7 milliseconds late, the ball will be foul past first, 7 milliseconds early, foul past third. That’s not much margin for error.

5. If the pitch moves enough in the last few feet, the information literally cannot get from eye to brain to muscle to action in time for the batter to react. Advantage pitcher—and that explains why occasionally the batter swings at pitches which arrive at the plate really far out of the strike zone, or swings so hard they fall down.

6. Certain players seem to do the “shuffle the deck of cards” very quickly, and don’t (or can’t) use that extra 50 milliseconds to adjust their swing: they stick with the initial “read” of the ball. That may or may not be accurate, depending on the player’s experience and the expertise of the pitcher.

7. The additional time that a curve ball (or knuckleball!) travels gives the batter additional time to evaluate the pitch and make a better decision, but that is offset by the potential for late movement on the pitches. That’s why we pay Scherzer $210M, and Dan Haren is retired.

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