• 7.2 baseline — 0.6 × season 6.9 (19 gm) + 0.4 × last 10 7.6
• +0.2 opponent leak — they concede 158.8/game vs a 155.4 league average
• −2.5 at this ground — averages 4.7 there (25 gm)
• vs them: averages 4.7 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.