• 6.6 baseline — 0.6 × season 6.7 (13 gm) + 0.4 × last 10 6.5
• +0.0 opponent leak — they concede 155.9/game vs a 155.4 league average
• −0.5 at this ground — averages 6.2 there (37 gm)
• vs them: averages 5.9 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.