• 1.9 baseline — 0.6 × season 1.6 (18 gm) + 0.4 × last 10 2.3
• +0.1 opponent leak — they concede 13.6/game vs a 12.8 league average
• +0.5 at this ground — averages 2.4 there (16 gm)
• −0.5 wet forecast — averages 1.4 in the wet (8 gm)
• vs them: averages 2.1 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: 5 — far outside his usual range; kept in the average, not smoothed away.