• 4.1 baseline — 0.6 × season 4.0 (20 gm) + 0.4 × last 10 4.2
• +0.0 opponent leak — they concede 57/game vs a 56.6 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing
• +0.4 wet forecast — averages 4.5 in the wet (8 gm)
• vs them: averages 5.9 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. Round 17: 10 — far outside his usual range; kept in the average, not smoothed away.