• 1.0 baseline — 0.6 × season 0.9 (7 gm) + 0.4 × last 10 1.1
• +0.1 opponent leak — they concede 37.8/game vs a 35.7 league average
• +0.8 at this ground — averages 1.8 there (24 gm)
• vs them: averages 2.7 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.