• 4.5 baseline — 0.6 × season 4.6 (18 gm) + 0.4 × last 10 4.4
• +0.1 opponent leak — they concede 219.6/game vs a 213.6 league average
• +0.9 at this ground — averages 5.4 there (10 gm)
• vs them: averages 4.5 over 8 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 15: 11 — far outside his usual range; kept in the average, not smoothed away.