• 4.5 baseline — 0.6 × season 4.6 (5 gm) + 0.4 × last 10 4.3
• +0.7 opponent leak — they concede 108.9/game vs a 93.4 league average
• +0.5 at this ground — averages 5 there (8 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.