• 1.1 baseline — 0.6 × season 0.9 (15 gm) + 0.4 × last 10 1.3
• −0.0 opponent leak — they concede 12.2/game vs a 12.8 league average
• +0.9 at this ground — averages 2 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.