• 1.9 baseline — 0.6 × season 1.8 (17 gm) + 0.4 × last 10 2.2
• +0.2 opponent leak — they concede 39/game vs a 35.7 league average
• −1.6 at this ground — averages 0.3 there (13 gm)
• −0.4 wet forecast — averages 1.6 in the wet (14 gm)
• vs them: averages 0.9 over 8 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 8: 6 — far outside his usual range; kept in the average, not smoothed away.