• 9.7 baseline — 0.6 × season 10.4 (16 gm) + 0.4 × last 10 8.5
• +0.5 opponent leak — they concede 164/game vs a 155.4 league average
• −0.7 at this ground — averages 8.9 there (39 gm)
• vs them: averages 9.3 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.