• 11.3 baseline — 0.6 × season 11.3 (20 gm) + 0.4 × last 10 11.1
• +1.0 opponent leak — they concede 233.1/game vs a 213.6 league average
• +1.7 at this ground — averages 12.9 there (22 gm)
• wet forecast: too thin to count (3 gm) — shown, adds nothing
• vs them: averages 11.5 over 2 games — evidence, never summed

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.