• 1.6 baseline — 0.6 × season 1.6 (16 gm) + 0.4 × last 10 1.6
• +0.1 opponent leak — they concede 33.9/game vs a 32.7 league average
• +0.3 at this ground — averages 2 there (23 gm)
• vs them: averages 2.2 over 6 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 5: 5 — far outside his usual range; kept in the average, not smoothed away.