• 3.8 baseline — 0.6 × season 4.0 (8 gm) + 0.4 × last 10 3.4
• +0.1 opponent leak — they concede 158.8/game vs a 155.4 league average
• +0.8 at this ground — averages 4.6 there (7 gm)

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.