• 1.8 baseline — 0.6 × season 1.9 (20 gm) + 0.4 × last 10 1.6
• +0.4 opponent leak — they concede 15.6/game vs a 12.8 league average
• −0.0 at this ground — averages 1.7 there (26 gm)
• wet forecast: too thin to count (3 gm) — shown, adds nothing
• vs them: averages 2.7 over 3 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.