• 1.3 baseline — 0.6 × season 1.5 (15 gm) + 0.4 × last 10 1.1
• −0.1 opponent leak — they concede 87/game vs a 93.4 league average
• −0.2 at this ground — averages 1.1 there (8 gm)
• wet forecast: too thin to count (2 gm) — shown, adds nothing
• vs them: averages 1.2 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.