• 0.6 baseline — 0.6 × season 0.4 (20 gm) + 0.4 × last 10 0.8
• −0.0 opponent leak — they concede 22.6/game vs a 23.7 league average
• −0.2 at this ground — averages 0.4 there (61 gm)
• −0.3 wet forecast — averages 0.3 in the wet (14 gm)
• vs them: averages 0.7 over 12 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 13: 4 — far outside his usual range; kept in the average, not smoothed away. Round 17: 4 — far outside his usual range; kept in the average, not smoothed away.