• 7.2 baseline — 0.6 × season 7.5 (19 gm) + 0.4 × last 10 6.9
• +0.8 opponent leak — they concede 104/game vs a 93.4 league average
• +0.9 at this ground — averages 8.2 there (59 gm)
• vs them: averages 9.8 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.