• 7.2 baseline — 0.6 × season 8.0 (20 gm) + 0.4 × last 10 5.9
• −0.1 opponent leak — they concede 153.7/game vs a 155.4 league average
• −1.6 at this ground — averages 5.6 there (74 gm)
• vs them: averages 4.4 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.