• 6.9 baseline — 0.6 × season 6.7 (20 gm) + 0.4 × last 10 7.3
• +0.5 opponent leak — they concede 230.1/game vs a 213.6 league average
• −0.9 at this ground — averages 6.1 there (67 gm)
• vs them: averages 5.6 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 18: 13 — far outside his usual range; kept in the average, not smoothed away.