• 4.7 baseline — 0.6 × season 4.8 (20 gm) + 0.4 × last 10 4.6
• −0.6 opponent leak — they concede 80.8/game vs a 93.4 league average
• +0.8 at this ground — averages 5.5 there (64 gm)
• vs them: averages 4.1 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 6: 11 — far outside his usual range; kept in the average, not smoothed away.