• 3.9 baseline — 0.6 × season 4.1 (19 gm) + 0.4 × last 10 3.6
• +0.2 opponent leak — they concede 164/game vs a 155.4 league average
• −0.0 at this ground — averages 3.9 there (31 gm)
• vs them: averages 4.2 over 10 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: 12 — far outside his usual range; kept in the average, not smoothed away.