I see, said the momentarily-blind batter

You hear it all the time, “Keep your eye on the ball.”

The problem is, hitters are rarely—if ever—able to carry out the task. The human eye, with all its complexity, just can’t keep up with the simple task of tracking a ball.*

* Okay, there may exist a few special athletes who have been able to do it. For the 99.999 percent of the rest, it is true. So, yes. Somebody like Ted Williams very well may have been able to watch the ball all the way. He is a unique case.

Vision is complex function of the human body. There are several ways the eye keeps an object in focus using different parts of the brain. Each way is also affected differently by fatigue, drug/alcohol usage, etc. It is a marvel that we can focus on anything at all.

Let’s take a walk down all the functions the batter’s eyes have to perform when attempting to track a pitch to hit.

First, he has to watch the pitcher wind up and locate the pitch coming out of the pitcher’s hand. At this point, the pitch appears to be directly in front of the batter, at 180 degrees (or zero degrees, whichever makes you happy). The batter has little but his memory and a good guess to determine the speed of the ball at that time. There is little to help him estimate the speed and movement based on the background.

I think of it like this: At this point he is standing on a boat looking toward the horizon and seeing a boat coming toward him.

Now he has a ball traveling at some speed in his line of vision. It is quickly coming toward him, starting to no longer be in front of him, but in a path that will lead the ball to be 90 degrees to him when it crosses the plate. This is when batter will notice the spin of the stitches (if he can determine it). He’ll start to get a better guess on the speed of the pitch and a general idea of the path of the pitch.

He’ll use this information and filter it through memory to determine the type of pitch. There will be a general bias toward the type of pitch he THINKS the pitcher was going to throw and where he thinks the pitcher will locate it. (This natural bias is sometimes referred to as heuristics. There are many common heuristics that take place in an at-bat).

Now, standing on your boat, the ship that was on the horizon is closer, moving faster, and you are able to see more detail on the boat.

At this time, the batter needs to determine if he’ll swing at the pitch and start his body in motion if he is. At this point, the ball’s angle is moving from 180 degrees toward 90. The batter can get a little better judge of the speed. But it is also closer, moving faster. This will cause moving from one type of vision to another.

At the same time, if the batter is going to swing, his body is moving, so another type of vision also will be active. Now the brain has to process several different types of visual information, getting the body moving and coordinate everything. Being good at this process is what makes a good hitter. Being able to upset this process is what makes a good pitcher.

“Hitting is timing. Pitching is upsetting timing.”
Warren Spahn

Now you are attempting to keep an eye on the boat that was on the horizon. Move to start your boat and try to formulate a plan to catch up with the boat now about to pass you.

It is about this point that, unknown to the batter, he makes a decision. He’ll either continue to follow the ball as long as he can, or he’ll move his eyes to where he thinks the ball and bat will meet. If he moves to where he thinks the ball will go, there is a good chance he’ll see the ball hit the bat or see his swing miss. If he attempts to follow the ball, the ball will eventually move faster than his eyes can keep up. In both cases, the batter will take his eyes off the ball.

Throughout this baseball season, I’ll describe the timing involved with the process above, including some of the latency in both “thinking’’ and the visual process. I’ll use that to look at different ways both the pitcher and batter might be able to use this information.

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It is not a perfect program, but it certainly counts as progress.

Using PITCHf/x data, I’ll look at ways, perhaps unknown to them, pitchers and batters exploit this already. Then, I’ll debunk the hanging curveball and the hopping fastball. After the season, I’ll see if I can label hitters as ones who follow the ball as long as they can or look where they predict the ball will go, and if one type is a better hitter than the other.*

* It is my hope to have this debunked by a nephrologist and a professor of legal studies. Yes, I want to be in “The Beauty of Short Hops 2: Electric Boogaloo”.

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All true. Covered by Epstein some years back though his mechanics model is flawed. Your point about the limits of vision also explains why it’s important to get the eyes as low as possible when fielding a ground ball. The lower the eyes/the closer to the track of the ball, the longer the ground ball can be tracked with the eyes.