• 1.9 baseline — 0.6 × season 1.8 (20 gm) + 0.4 × last 10 2.0
• +0.0 opponent leak — they concede 57/game vs a 56.6 league average
• +0.9 wet forecast — averages 2.8 in the wet (8 gm)
• vs them: averages 2.3 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 21: 7 — far outside his usual range; kept in the average, not smoothed away.