• 7.1 baseline — 0.6 × season 6.8 (20 gm) + 0.4 × last 10 7.5
• +0.5 opponent leak — they concede 60.6/game vs a 56.6 league average
• −0.6 at this ground — averages 6.5 there (50 gm)
• vs them: averages 6.7 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: 14 — far outside his usual range; kept in the average, not smoothed away.