• 9.8 baseline — 0.6 × season 10.2 (16 gm) + 0.4 × last 10 9.2
• −0.1 opponent leak — they concede 210.3/game vs a 213.6 league average
• +2.9 at this ground — averages 12.7 there (30 gm)
• vs them: averages 13.8 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 9: 1 — far outside his usual range; kept in the average, not smoothed away.