• 1.2 baseline — 0.6 × season 1.0 (16 gm) + 0.4 × last 10 1.6
• −0.1 opponent leak — they concede 22.6/game vs a 23.6 league average
• +0.4 at this ground — averages 1.6 there (56 gm)
• −0.7 wet forecast — averages 0.6 in the wet (14 gm)
• vs them: averages 0.9 over 9 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 13: 8 — far outside his usual range; kept in the average, not smoothed away.