• 3.5 baseline — 0.6 × season 3.5 (6 gm) + 0.4 × last 10 3.6
• +0.1 opponent leak — they concede 160.7/game vs a 155.4 league average
• +0.6 at this ground — averages 4.1 there (10 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.