• 5.3 baseline — 0.6 × season 5.3 (12 gm) + 0.4 × last 10 5.4
• −0.3 opponent leak — they concede 200.3/game vs a 213.6 league average
• +0.3 at this ground — averages 5.6 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.