• 9.5 baseline — 0.6 × season 9.5 (20 gm) + 0.4 × last 10 9.5
• +0.2 opponent leak — they concede 219.2/game vs a 213.6 league average
• −1.4 at this ground — averages 8.1 there (36 gm)
• vs them: averages 7.4 over 5 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.