• 9.9 baseline — 0.6 × season 10.3 (20 gm) + 0.4 × last 10 9.3
• +0.0 opponent leak — they concede 213.7/game vs a 213.6 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing
• +3.3 wet forecast — averages 13.1 in the wet (8 gm)
• vs them: averages 12.0 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.