• 37.3 baseline — 0.6 × season 36.7 (17 gm) + 0.4 × last 10 38.1
• +0.5 opponent leak — they concede 349.4/game vs a 344.7 league average
• +1.1 at this ground — averages 38.4 there (19 gm)
• vs them: averages 35.7 over 11 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.