• 3.6 baseline — 0.6 × season 3.6 (10 gm) + 0.4 × last 10 3.6
• +0.2 opponent leak — they concede 164.6/game vs a 155.4 league average
• +0.1 at this ground — averages 3.7 there (24 gm)
• vs them: averages 2.0 over 2 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.