• 1.6 baseline — 0.6 × season 1.5 (16 gm) + 0.4 × last 10 1.7
• +0.2 opponent leak — they concede 64.2/game vs a 56.6 league average
• +0.3 at this ground — averages 1.8 there (65 gm)
• vs them: averages 1.7 over 11 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 9: 4 — far outside his usual range; kept in the average, not smoothed away.