• 8.3 baseline — 0.6 × season 8.2 (19 gm) + 0.4 × last 10 8.4
• −0.5 opponent leak — they concede 201.8/game vs a 213.6 league average
• −1.0 at this ground — averages 7.3 there (54 gm)
• vs them: averages 7.0 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 10: 15 — far outside his usual range; kept in the average, not smoothed away.