• 16.6 baseline — 0.6 × season 16.1 (14 gm) + 0.4 × last 10 17.3
• −0.5 opponent leak — they concede 357.8/game vs a 369 league average
• at this ground: too thin to count (3 gm) — shown, adds nothing
• +1.9 wet forecast — averages 18.5 in the wet (4 gm)
• vs them: averages 18.0 over 1 game — 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.