• 6.9 baseline — 0.6 × season 5.6 (5 gm) + 0.4 × last 10 8.8
• +0.4 opponent leak — they concede 224.7/game vs a 213.6 league average
• −0.6 at this ground — averages 6.3 there (7 gm)
• vs them: averages 7.9 over 8 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.