• 7.0 baseline — 0.6 × season 7.2 (19 gm) + 0.4 × last 10 6.7
• −0.4 opponent leak — they concede 200.3/game vs a 213.6 league average
• −1.5 at this ground — averages 5.6 there (9 gm)
• vs them: averages 7.0 over 6 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.