• 1.5 baseline — 0.6 × season 1.5 (6 gm) + 0.4 × last 6 1.5
• +0.1 opponent leak — they concede 100.5/game vs a 93.4 league average
• +0.3 at this ground — averages 1.8 there (4 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.