• 10.1 baseline — 0.6 × season 10.1 (9 gm) + 0.4 × last 10 10.1
• −0.6 opponent leak — they concede 200.3/game vs a 213.6 league average
• +1.6 at this ground — averages 11.7 there (12 gm)
• vs them: averages 11.5 over 8 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.