• 6.8 baseline — 0.6 × season 6.8 (16 gm) + 0.4 × last 10 7.0
• +0.0 opponent leak — they concede 155.9/game vs a 155.4 league average
• −0.9 at this ground — averages 6 there (40 gm)
• vs them: averages 5.2 over 9 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.