• 4.0 baseline — 0.6 × season 4.1 (15 gm) + 0.4 × last 10 4.0
• +0.3 opponent leak — they concede 38/game vs a 35.7 league average
• +1.0 at this ground — averages 5 there (8 gm)
• wet forecast: too thin to count (2 gm) — shown, adds nothing
• vs them: averages 4.0 over 5 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.