• 11.4 baseline — 0.6 × season 11.2 (17 gm) + 0.4 × last 10 11.7
• +0.2 opponent leak — they concede 158.8/game vs a 155.4 league average
• +3.1 at this ground — averages 14.5 there (11 gm)
• vs them: averages 12.8 over 9 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 17: 19 — far outside his usual range; kept in the average, not smoothed away.