Protocol before numbers

Every number on this page carries the same three qualifiers: internal evaluation, a deliberately small held-out corpus, self-supervised training. They bound what the results mean — strong evidence of what the architecture can learn, not benchmark claims. The protocol is built around leave-one-match-out (LOMO) cross-validation, so scores are never earned on movement the model memorized — a discipline that becomes more binding as the corpus grows.

Masked reconstruction

Prototype

Reconstruction error is measured as MPJPE — mean per-joint position error — under the structured masks described in the training documentation. Difficulty scales exactly as it should: scattered masks are easy, contiguous space-time holes are hard.

Mask typeMPJPEFraming
random joints2.7 cminternal · small held-out corpus · self-supervised
temporal block4.2 cminternal · small held-out corpus · self-supervised
graph-temporal8.5 cminternal · small held-out corpus · self-supervised

Concept probes

Prototype

A linear probe asks a hard question gently: can a straight line through the frozen embedding recover a physical quantity the model was never told about? For body-mechanics concepts the answer is emphatic — speed, trunk lean, and left-right knee asymmetry are all linearly readable. That is the intended shape of the representation: the model learned how the body moves without a single label.

ConceptFraming
speed profile0.95internal · small held-out corpus · self-supervised
torso lean0.91internal · small held-out corpus · self-supervised
knee asymmetry0.88internal · small held-out corpus · self-supervised

Structure without supervision

Beyond point metrics, the suite checks that the embedding space is organized: unsupervised clustering over movement windows recovers coherent movement archetypes without any event feed, and transitions between clusters align with visible changes on video. Archetype counts and quality scores stay internal until the corpus is large enough to publish them responsibly.

What the numbers do not show — tactical context, opponent pressure, match state — is deliberately out of scope: the model sees the body, not the pitch.