• 4.3 baseline — 0.6 × season 4.3 (8 gm) + 0.4 × last 8 4.3
• +0.4 opponent leak — they concede 101.3/game vs a 93.4 league average
• +0.4 at this ground — averages 4.7 there (6 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.