• 6.8 baseline — 0.6 × season 6.8 (16 gm) + 0.4 × last 10 6.7
• +1.1 opponent leak — they concede 108.9/game vs a 93.4 league average
• +0.6 at this ground — averages 7.4 there (41 gm)
• vs them: averages 8.2 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.