Pitch Zone Change Effectiveness

Seeking Better Pitch Sequences

If the pitcher’s objective is to deceive the hitter, then, of course, they must have good pitches that are hard to identify by the hitter. This means they move in pronounced or unanticipated ways and they look similar enough to other pitches in the repertoire that they are hard to distinguish.

However, I believe that the pitches seen recently by the hitter also affect their ability to recognize and react to pitches they are seeing in the present. Changes in speed, location, and break can throw off a hitter’s timing, focal points, and mechanics. Success on confusing any of these critical elements of hitting would improve the pitcher’s chance of success.

My Hypothesis: Location Matters

In this study, I’ll examine the effects of location change on Pitcher success. Location is measured on the X (inside/outside) and Z (high/low) axes, so we will look into how changes from pitch-to-pitch along these axes affects Pitcher success.

To gauge Pitch Success, we will use a simple proxy for hitter confusion & deception: swing-and-miss (aka whiff) rates. For all possible directions and magnitudes of location change, we’ll measure the relative frequency of swings, contact, and whiffs.

The interactive heatmap below shows the swing, contact, and whiff rates after a pitcher changes locations from the immediately preceding pitch.

• The X-Axis represents the change of position relative to the hitter across the plate, with positive numbers indicating movement away from the hitter / outside, and negative numbers indicating moving towards the hitter / inside. For scale, the strike zone is 3 zones wide.
• The Z-Axis represents the change of pitch height when it crosses the plate. For scale, the strike zone is 3 zones high.

The most immediate take-aways from the heatmap above are:

1. Staying in the same place will induce the most swings
2. Staying in the same place will also induce higher contact rates
3. Moving down in location will induce higher whiff rates

Practical Implications

Depending on the pitcher’s at-bat level strategy for a hitter (e.g. pitch around, avoid contact, induce weak contact), they can construct 1-2 pitch combinations that will increase their chances of success.

1. If a pitcher is trying to avoid contact, then constructing pitch sequences that start high and progressively step-down in the zone should create more whiffs as the hitter is less capable of adjusting their swing down.
2. If a pitcher is trying to induce weak contact, keep pitches around the same location to induce more swings and contact, but use other tactics to diminish the quality of contact.