• 10.6 baseline — 0.6 × season 11.0 (7 gm) + 0.4 × last 10 9.9
• +0.6 opponent leak — they concede 389.2/game vs a 369 league average
• −1.4 at this ground — averages 9.2 there (10 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.