• 9.2 baseline — 0.6 × season 9.3 (9 gm) + 0.4 × last 10 9.1
• +0.2 opponent leak — they concede 219.2/game vs a 213.6 league average
• −0.7 at this ground — averages 8.6 there (27 gm)
• vs them: averages 10.3 over 3 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.