• 1.3 baseline — 0.6 × season 1.2 (18 gm) + 0.4 × last 10 1.5
• +0.1 opponent leak — they concede 10.2/game vs a 9.4 league average
• −0.6 at this ground — averages 0.8 there (16 gm)
• −0.2 wet forecast — averages 1.1 in the wet (8 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 11: 4 — far outside his usual range; kept in the average, not smoothed away.