• 152.3 baseline — 0.6 × season 152.3 (10 gm) + 0.4 × last 10 152.3
• +13.7 opponent leak — they concede 1838.8/game vs a 1686.6 league average
• +15.1 at this ground — averages 167.4 there (5 gm)
• vs them: averages 149.0 over 2 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 12: 22 — far outside his usual range; kept in the average, not smoothed away.