• 11.0 baseline — 0.6 × season 10.8 (20 gm) + 0.4 × last 10 11.3
• −1.0 opponent leak — they concede 141.4/game vs a 155.4 league average
• −3.2 at this ground — averages 7.8 there (86 gm)
• vs them: averages 7.9 over 9 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.