• 0.4 baseline — 0.6 × season 0.2 (6 gm) + 0.4 × last 10 0.8
• +0.0 opponent leak — they concede 57.5/game vs a 56.6 league average
• +0.4 at this ground — averages 0.8 there (50 gm)
• vs them: averages 1.0 over 7 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 9: 5 — far outside his usual range; kept in the average, not smoothed away.