Metric · NBA

Defensive Impact

v2.0.0

Publish the defensive component of the same role-relative, minute-shrunk descriptive index used by UB Impact.

D_{r a w} = 0.30 z (S T L_{36}) + 0.30 z (B L K_{36}) + 0.30 z (D R E B_{36}) - 0.10 z (P F_{36})

Defensive event inputs are standardized within the declared role bucket.

What it measures

Defensive events are standardized within role bucket and exposure-shrunk; the component remains explicitly incomplete without tracking or matchup data.

How to read it

Higher values indicate stronger descriptive defensive impact.

Why it exists

Defence is the less complete half of public box-score evidence, so it is published as a diagnostic component rather than a causal defensive estimate. It shares the canonical role buckets, eligibility, minute shrinkage, and scale with the total.

Limits

This component is diagnostic; the published total requires both components and uses the governed 0.60/0.40 blend.
Event-based defensive inputs reward activity and under-credit deterrence and positioning.
The foul penalty is a fixed weight and does not distinguish shooting fouls from take fouls.

Calculation, evidence, and implementation

Calculation

D = c l am p (50 + 10 \frac{M I N}{M I N + 1200} D_{r a w}, 0, 100)

The component uses the same minute exposure shrinkage and display scale as UB Impact.

Inputs

Stl 36, Blk 36, Dreb 36, Pf 36, Min, Gp

Methodology

Role-bucket z-score aggregation with minute shrinkage; component output from the canonical NBA player-season ETL.

Normalization

0-100 index with 50 as the eligible-population center.

Uncertainty

No confidence interval is published; eligibility and exposure are the available reliability signals.

Evaluation

Directionality and stability checks; not a causal or predictive estimate.

Sources

Pipelines/NBA Ingest/Stats.Py

Implementation

Registry identifier: NBA_IMPACT_DEFENSE. Version 2.0.0; status drafted.

Metric distribution →General methodology →