• 11.9 baseline — 0.6 × season 11.8 (12 gm) + 0.4 × last 10 12.2
• −0.8 opponent leak — they concede 343.2/game vs a 369 league average
• −0.6 at this ground — averages 11.3 there (7 gm)
• vs them: averages 9.7 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 19: 20 — far outside his usual range; kept in the average, not smoothed away.