• 46.2 baseline — 0.6 × season 48.8 (20 gm) + 0.4 × last 10 42.3
• +4.2 opponent leak — they concede 1838.8/game vs a 1686.6 league average
• +38.5 at this ground — averages 84.7 there (35 gm)
• vs them: averages 81.9 over 7 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.