• 9.6 baseline — 0.6 × season 9.5 (20 gm) + 0.4 × last 10 9.7
• +0.5 opponent leak — they concede 164/game vs a 155.4 league average
• −0.1 at this ground — averages 9.5 there (70 gm)
• vs them: averages 8.6 over 10 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.