• 6.5 baseline — 0.6 × season 6.0 (20 gm) + 0.4 × last 10 7.2
• −0.1 opponent leak — they concede 35.2/game vs a 35.7 league average
• −0.5 at this ground — averages 6 there (83 gm)
• vs them: averages 5.3 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.