• 11.0 baseline — 0.6 × season 11.4 (19 gm) + 0.4 × last 10 10.4
• −0.2 opponent leak — they concede 363.9/game vs a 369 league average
• −1.4 at this ground — averages 9.6 there (30 gm)
• vs them: averages 8.3 over 7 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.