• 21.6 baseline — 0.6 × season 22.0 (8 gm) + 0.4 × last 10 21.0
• −0.7 opponent leak — they concede 357.8/game vs a 369 league average
• vs them: averages 20.3 over 3 games — evidence, never summed

Derived, not measured — plain arithmetic over his real games, shown in full. Adjustments can overlap (a game at this ground can also be a wet one); they add simply, and this note is the admission.