• 8.9 baseline — 0.6 × season 9.3 (20 gm) + 0.4 × last 10 8.3
• −0.4 opponent leak — they concede 203.2/game vs a 213.6 league average
• −0.7 at this ground — averages 8.3 there (92 gm)
• vs them: averages 8.2 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 14: 3 — far outside his usual range; kept in the average, not smoothed away.