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MLB / Descriptive sequencing

Published pitch transitions by count class.

This matrix records the published conditional frequency of a next pitch type given the previous pitch type, within a plate appearance. It is a descriptive view of the local Statcast pull.

Reading trail

Read first: Read the pitch-type distribution before interpreting a transition row.

Next question: Which count states change the published pitch sequence?

Read the analysis: Pitch velocity shape: what the distribution says, and what it does not

PaperSupporting sourcePitch velocity shape: what the distribution says, and what it does notMLB | as_of 2026-09-16PaperSupporting sourceWhat the count does to the next pitchMLB | as_of 2026-09-16ModuleSupporting sourcePitch SequencingMLB | as_of 2026-07-25AnalysisSame entity typeMLB pitch type atlas measurementsMLB | as_of 2025-09-28AnalysisSame entity typeMLB team pitch atlas measurementsMLB | as_of 2025-09-28

all: every transition (unconditional; charted matrix)

Published axis coverage: 95.5%

Behind, even, and ahead are disjoint classes. Two-strike and three-ball are overlapping views, not additive classes.

Previous pitch to next pitch
Rows are the previous pitch type; columns are the next pitch type. Select a cell for its published details.

Sequential scale: 0.0% to 43.2%; hatched cells: below published floor.

Previous pitchNext pitchFFSISLCHSTFCCUFSFF43.2%6.1%14.7%11.2%6.1%5.3%6.7%3.9%SI13.5%36.0%13.1%9.7%10.5%7.6%5.4%2.1%SL31.1%13.1%35.4%7.8%2.7%2.7%3.9%2.3%CH33.7%11.0%8.4%29.1%4.3%6.8%5.2%0.1%ST25.7%19.5%4.2%7.7%31.8%6.0%2.5%1.9%FC22.1%15.3%7.1%10.7%8.0%25.2%6.7%2.9%CU31.5%11.7%8.4%12.7%2.7%7.0%21.8%4.0%FS33.3%6.8%8.0%0.3%3.2%5.8%4.5%36.7%
Each probability uses the complete published row denominator. Rows can total below 100% because next-pitch types outside the displayed axis remain off-axis.
public/data/showcase/pitch_sequencing.jsonSource as of 2026-07-25n not published
all conditional pitch sequencing probabilities
Previous pitchPublished row denominatorFFSISLCHSTFCCUFS
FF165,179
SI77,127
SL73,567
CH51,941
ST39,607
FC39,125
CU35,596
FS16,141

Selected transition

FF to FF

Count
71,414
Row denominator
165,179
Conditional probability
43.2%

Source fields: pitch_sequencing.json -> pitch_types[], by_class[].prob_matrix[row][column], count_matrix[row][column], row_n_from[row], row_below_floor[row], coverage, and floors.row_min_n.