• 1.2 baseline — 0.6 × season 1.2 (9 gm) + 0.4 × last 10 1.2
• +0.0 opponent leak — they concede 12.3/game vs a 12.2 league average
• +0.3 at this ground — averages 1.6 there (9 gm)
• +0.0 wet forecast — averages 1.3 in the wet (4 gm)
• vs them: averages 0.8 over 5 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.