3 Pitch Paths

Pitch Selection is like Cold War game theory.

The pitcher/catcher (Battery) and the Hitter are trying to balance a guessing game of what their counterpart is thinking with their own capabilities to develop a decision or expectation about the next pitch thrown.


The Battery is trying to strike the delicate balance of a pitch that will result in a strike or an out (usually by being put into play) and give the hitter the least opportunity to get on-base. The Hitter is trying to anticipate that decision to maximize their ability to react successfully. This becomes circular since the Hitter’s ability to anticipate correctly improves their ability to get on-base, which changes the calculus and pitch decision for the Battery, which changes the Hitter’s ability to anticipate correctly. Just like the nuclear stand-off of the Cold War. A low-and-inside slider hit into the gap or a Soviet Sarmak from Siberia shot down by Star Wars lasers: same thing.

Pitcher: I should throw this.


Hitter: I will anticipate this.

Pitcher: Then I should throw that.

But it’s not – because baseball is fun and the Cold War was humans (not) trying to murder each other by the millions. Instead let’s say pitch selection is just like keeping secrets from your Friends:

So given this stand-off of anticipation, the Battery can take one of two approaches:

1.) complete randomness, or

2.) sequencing pitches that build on each other to keep the hitter off balance.

This is old pitching-coach-speak of ‘changing the hitter’s eye level, keeping him on his heels, and mixing speeds’.

Understanding The Pitch Decision

I’ll endeavor to do more work on the effectiveness of these pitch sequences, but we can start by looking at their prevalence. Do pitchers revert to predictable patterns? Are their common 1-2-3 combinations of pitches based on empirical observation? To explore this, I built the 3 Pitch Path Tool below, which analyzes pitches from the 2018 Major League Baseball season to try to determine patterns and probabilities for “what’s he going to throw next?”.


So what can we learn from this?

There are definite trends in pitch decisions. For example, after throwing two Four Seam Fastballs right down the middle, a hitter would be best advised to look for another fastball, but at the edges/outside of the zone and probably a bad pitch to swing at.

Practical Implication:

In 2018 alone, there were over 76k different 3 Pitch Paths observed. To get utility from this insight, it takes focus. Individual Batteries have tendencies. The Hitter can be aware of the most prevalent 3 Pitch Paths for a pitcher they are facing, and the Battery can know their own tendencies so they can defy them.

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