• 19.4 baseline — 0.6 × season 19.5 (15 gm) + 0.4 × last 10 19.2
• −0.6 opponent leak — they concede 357.8/game vs a 369 league average
• +3.8 at this ground — averages 23.1 there (9 gm)
• +5.9 wet forecast — averages 25.2 in the wet (14 gm)
• vs them: averages 23.2 over 6 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: 0 — far outside his usual range; kept in the average, not smoothed away.