• 1.5 baseline — 0.6 × season 1.8 (16 gm) + 0.4 × last 10 1.2
• −0.1 opponent leak — they concede 22.6/game vs a 23.6 league average
• +0.4 at this ground — averages 1.9 there (17 gm)
• +0.9 wet forecast — averages 2.4 in the wet (5 gm)
• vs them: averages 0.0 over 1 game — 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 3: 8 — far outside his usual range; kept in the average, not smoothed away.