• 5.5 baseline — 0.6 × season 5.5 (12 gm) + 0.4 × last 10 5.4
• +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
• +0.4 wet forecast — averages 5.9 in the wet (9 gm)
• vs them: averages 7.3 over 8 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.