• 11.1 baseline — 0.6 × season 11.3 (7 gm) + 0.4 × last 10 10.9
• +0.5 opponent leak — they concede 386.2/game vs a 369 league average
• −0.5 at this ground — averages 10.6 there (5 gm)
• vs them: averages 12.0 over 1 game — 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.