• 43.8 baseline — 0.6 × season 43.3 (12 gm) + 0.4 × last 10 44.6
• +4.0 opponent leak — they concede 1838.8/game vs a 1686.6 league average
• +2.4 at this ground — averages 46.2 there (32 gm)
• vs them: averages 48.0 over 9 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.