• 6.8 baseline — 0.6 × season 6.6 (17 gm) + 0.4 × last 10 7.1
• +0.4 opponent leak — they concede 224.7/game vs a 213.6 league average
• +1.1 at this ground — averages 7.9 there (38 gm)
• vs them: averages 8.3 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.