• 1.2 baseline — 0.6 × season 1.2 (12 gm) + 0.4 × last 10 1.2
• +0.2 opponent leak — they concede 4/game vs a 3.5 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• −0.6 wet forecast — averages 0.6 in the wet (10 gm)
• vs them: averages 0.6 over 9 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.