• 6.5 baseline — 0.6 × season 6.6 (11 gm) + 0.4 × last 10 6.4
• −0.0 opponent leak — they concede 212.8/game vs a 213.6 league average
• +1.6 at this ground — averages 8.1 there (7 gm)
• vs them: averages 7.3 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.