• 11.9 baseline — 0.6 × season 11.8 (12 gm) + 0.4 × last 10 12.2
• +0.7 opponent leak — they concede 389.2/game vs a 369 league average
• −1.5 at this ground — averages 10.4 there (72 gm)
• vs them: averages 10.0 over 5 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 19: 20 — far outside his usual range; kept in the average, not smoothed away.