• 152.3 baseline — 0.6 × season 152.3 (10 gm) + 0.4 × last 10 152.3
• −9.9 opponent leak — they concede 1576.6/game vs a 1686.6 league average
• +41.2 at this ground — averages 193.5 there (23 gm)
• vs them: averages 116.3 over 3 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.