• 7.9 baseline — 0.6 × season 8.2 (6 gm) + 0.4 × last 10 7.5
• +0.2 opponent leak — they concede 158.8/game vs a 155.4 league average
• +3.1 at this ground — averages 11 there (34 gm)
• vs them: averages 9.2 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.