• 4.2 baseline — 0.6 × season 3.2 (6 gm) + 0.4 × last 10 5.7
• +0.2 opponent leak — they concede 225.5/game vs a 213.6 league average
• +1.0 at this ground — averages 5.1 there (15 gm)
• vs them: averages 11.0 over 1 game — 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: 16 — far outside his usual range; kept in the average, not smoothed away.