• 11.2 baseline — 0.6 × season 11.0 (17 gm) + 0.4 × last 10 11.4
• −0.7 opponent leak — they concede 345.4/game vs a 369 league average
• +0.9 at this ground — averages 12.1 there (49 gm)
• vs them: averages 13.3 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.