• 8.7 baseline — 0.6 × season 9.0 (14 gm) + 0.4 × last 10 8.2
• +0.5 opponent leak — they concede 164/game vs a 155.4 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing
• −0.1 wet forecast — averages 8.6 in the wet (7 gm)
• vs them: averages 11.8 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.