Does Sequencing Really Matter?
As a former high school pitching coach and D3 pitcher, I always believed in the art of pitch calling and that it was a skill that could be perfected through preparation, a connection with each pitcher and catcher, and the ability to adapt during the game. I would have been the first person to tell you that pitch sequencing was a key part of a successful outing.
Sequencing is the process of deciding which pitch should be thrown next based on the previous pitch. Pitchers, catchers, and pitching coaches are in a constant battle with hitters to keep the guessing game going about what’s coming next. To evaluate sequencing, I compared each pitch type by its individual performance versus being thrown twice consecutively (Double-Up), three times consecutively (Triple-Up), and even four times consecutively (Quadruple-Up). I also examined each unique two-pitch sequence and how the average of each of those sequences compared to all Double-Ups.
Using 2023 Trackman data from D1 teams, I compared whiff percentage (swing and miss divided by all swings), chase percentage (percent of all swings outside of the zone), and hard-hit percentage (balls in play +95mph) as the primary metrics for analysis.
Visualizing the Performance of Sequencing
The graphs above show that each pitch type is just as effective in isolation (single pitch) as when it is thrown 1–3 times in a row. Sliders and Changeups perform best, meaning off-speed pitches get more swings outside of the zone and result in weaker contact. I also found that whiff percentage follows a similar trend.
By taking the average results of all other sequences and comparing them to each pitch type’s Double-Up, there is further evidence suggesting that throwing a different pitch rather than repeating the previous one has no positive impact, as seen above. Throwing the same pitch twice outperforms the average results of sequencing in all areas except fastball whiffs.
Next, I looked into each sequence that encapsulated the average results in “All-All” above. The color for pitch corresponds to which pitch type is used as the current pitch.
Compared across each pitch type, there is little difference between unique sequences. Looking at whiff percentage, it is significantly worse to follow up any pitch with a fastball.
Modeling the Importance of Sequencing
To further investigate the impact of sequencing, I created a model that predicts run value based on each sequence after controlling for location. The following tables show the best and worst sequences from this model.
Controlling for location holds the skill level of command constant and puts a spotlight on just the effectiveness of the sequence. The best three sequences all ended in sliders. The worst three sequences were all fastballs and curveballs. This follows the same pattern expected with ranking pitch types by Stuff (sliders rank high while fastballs and curveballs are low), leading us to conclude that the effectiveness of the current pitch is mostly influenced by Stuff and not impacted by which pitch was thrown before it.
What is Valuable?
If sequencing has little influence on pitch calling decisions, what does? How should we decide which pitches to throw?
The best thing we can do is to lean into each pitcher’s strengths. Their strength does not have to be their fastball, and most fastballs aren’t strong enough anyway. They should use their best pitches most often.
Coaches and players should understand which pitches can be thrown for either a strike or swing and miss. If their Stuff isn’t up to snuff, location has to be key.
Finally, there are some elements of pitch calling that I haven’t analyzed yet that may play a key role in altering sequencing decisions. For example, it may be beneficial to find and exploit the weaknesses of hitters by throwing certain pitches and focusing on certain locations that they struggle with. In the future, it would be interesting to research if or when it is more beneficial to stray from the pitcher’s strengths to attack a hitter’s weakness. I would also like to control for variables such as the quality of the hitter, the count, and other factors that could influence the effect of a sequence beyond just controlling for location.
Conclusion
How well a pitch performs is not heavily influenced by what was thrown before it. Although there are small differences between each sequence, it doesn’t give us enough reason to call pitches based on a sequence over the strengths that pitchers have with their pitch types, Stuff, and command.
Good pitches are good pitches regardless of the previous pitch. Pitching coaches and players may want to reevaluate why they choose to throw certain pitches and focus on the effectiveness of a pitch rather than what was thrown before it.
#MovingTheNeedle
