• 40.2 baseline — 0.6 × season 40.3 (20 gm) + 0.4 × last 10 40.1
• −1.4 opponent leak — they concede 333/game vs a 344.7 league average
• −4.7 at this ground — averages 35.5 there (26 gm)
• vs them: averages 24.5 over 8 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.