• 7.1 baseline — 0.6 × season 6.8 (15 gm) + 0.4 × last 10 7.6
• +0.2 opponent leak — they concede 160.7/game vs a 155.4 league average
• −0.1 at this ground — averages 7 there (42 gm)
• vs them: averages 8.5 over 10 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.