• 3.8 baseline — 0.6 × season 3.6 (20 gm) + 0.4 × last 10 4.2
• +0.0 opponent leak — they concede 186/game vs a 185.9 league average
• −0.4 at this ground — averages 3.4 there (19 gm)
• vs them: averages 3.5 over 4 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 18: 8 — far outside his usual range; kept in the average, not smoothed away.