• 8.3 baseline — 0.6 × season 8.2 (12 gm) + 0.4 × last 10 8.5
• +0.0 opponent leak — they concede 369.9/game vs a 369 league average
• −0.4 at this ground — averages 7.9 there (8 gm)
• vs them: averages 3.5 over 2 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.