• 9.6 baseline — 0.6 × season 8.7 (20 gm) + 0.4 × last 10 10.9
• +0.1 opponent leak — they concede 349.4/game vs a 344.9 league average
• +3.4 at this ground — averages 13 there (22 gm)
• vs them: averages 11.8 over 10 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 11: 33 — far outside his usual range; kept in the average, not smoothed away.