• 5.0 baseline — 0.6 × season 5.4 (5 gm) + 0.4 × last 10 4.4
• +0.3 opponent leak — they concede 225.5/game vs a 213.6 league average
• +0.3 at this ground — averages 5.3 there (12 gm)
• vs them: averages 3.3 over 3 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: 9 — far outside his usual range; kept in the average, not smoothed away.