• 4.8 baseline — 0.6 × season 4.7 (20 gm) + 0.4 × last 10 5.0
• +0.5 opponent leak — they concede 36.5/game vs a 32.8 league average
• −1.2 at this ground — averages 3.6 there (24 gm)
• vs them: averages 4.0 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 16: 13 — far outside his usual range; kept in the average, not smoothed away.