• 10.4 baseline — 0.6 × season 10.1 (20 gm) + 0.4 × last 10 10.9
• −0.5 opponent leak — they concede 203.2/game vs a 213.6 league average
• +0.8 at this ground — averages 11.2 there (50 gm)
• vs them: averages 10.2 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 16: 18 — far outside his usual range; kept in the average, not smoothed away.