• 16.7 baseline — 0.6 × season 16.7 (11 gm) + 0.4 × last 10 16.6
• +0.4 opponent leak — they concede 377.9/game vs a 369 league average
• +0.7 at this ground — averages 17.4 there (24 gm)
• vs them: averages 19.0 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 18: 7 — far outside his usual range; kept in the average, not smoothed away.