• 0.5 baseline — 0.6 × season 0.6 (20 gm) + 0.4 × last 10 0.4
• +0.0 opponent leak — they concede 25.6/game vs a 23.6 league average
• at this ground: too thin to count (3 gm) — shown, adds nothing
• −0.5 wet forecast — averages 0 in the wet (13 gm)
• vs them: averages 0.7 over 11 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.