Evaluation
Evaluation Suite
How the model is measured: masked-reconstruction error, concept probes, archetype clustering, and leave-one-match-out validation — internal evaluation on a deliberately small held-out corpus, fully self-supervised.
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
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 type | MPJPE | Framing |
|---|---|---|
| random joints | 2.7 cm | internal · small held-out corpus · self-supervised |
| temporal block | 4.2 cm | internal · small held-out corpus · self-supervised |
| graph-temporal | 8.5 cm | internal · small held-out corpus · self-supervised |
Concept probes
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.
| Concept | r² | Framing |
|---|---|---|
| speed profile | 0.95 | internal · small held-out corpus · self-supervised |
| torso lean | 0.91 | internal · small held-out corpus · self-supervised |
| knee asymmetry | 0.88 | internal · 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.