• 11.1 baseline — 0.6 × season 11.1 (19 gm) + 0.4 × last 10 11.2
• −0.7 opponent leak — they concede 345.4/game vs a 369 league average
• −1.9 at this ground — averages 9.2 there (9 gm)
• vs them: averages 11.5 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.