• 3.6 baseline — 0.6 × season 3.5 (8 gm) + 0.4 × last 10 3.7
• +0.2 opponent leak — they concede 225.5/game vs a 213.6 league average
• +0.3 at this ground — averages 3.8 there (6 gm)
• vs them: averages 6.0 over 1 game — 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.