• 7.3 baseline — 0.6 × season 7.1 (16 gm) + 0.4 × last 10 7.5
• +1.2 opponent leak — they concede 108.9/game vs a 93.4 league average
• +0.9 at this ground — averages 8.2 there (21 gm)
• vs them: averages 7.0 over 12 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.