• 1.6 baseline — 0.6 × season 1.7 (9 gm) + 0.4 × last 10 1.5
• −0.0 opponent leak — they concede 35.6/game vs a 35.7 league average
• −0.4 at this ground — averages 1.2 there (40 gm)
• vs them: averages 1.7 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.