• 3.0 baseline — 0.6 × season 3.0 (20 gm) + 0.4 × last 10 3.1
• −0.2 opponent leak — they concede 87/game vs a 93.4 league average
• at this ground: too thin to count (3 gm) — shown, adds nothing
• +0.6 wet forecast — averages 3.6 in the wet (13 gm)
• vs them: averages 3.6 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. Round 20: 7 — far outside his usual range; kept in the average, not smoothed away.