• 4.1 baseline — 0.6 × season 4.7 (16 gm) + 0.4 × last 10 3.1
• +0.0 opponent leak — they concede 186/game vs a 185.9 league average
• +3.2 at this ground — averages 7.2 there (18 gm)
• vs them: averages 10.0 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.