• 10.0 baseline — 0.6 × season 10.1 (8 gm) + 0.4 × last 10 9.7
• −0.1 opponent leak — they concede 211.7/game vs a 213.6 league average
• −1.1 at this ground — averages 8.9 there (46 gm)
• vs them: averages 10.7 over 6 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.