• 10.0 baseline — 0.6 × season 10.2 (20 gm) + 0.4 × last 10 9.7
• +0.8 opponent leak — they concede 230.1/game vs a 213.6 league average
• +0.0 at this ground — averages 10 there (6 gm)
• vs them: averages 14.0 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.