• 5.5 baseline — 0.6 × season 5.4 (13 gm) + 0.4 × last 10 5.6
• −0.6 opponent leak — they concede 82.5/game vs a 93.4 league average
• −1.2 at this ground — averages 4.3 there (4 gm)
• −1.6 wet forecast — averages 3.9 in the wet (18 gm)
• vs them: averages 4.5 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 16: 12 — far outside his usual range; kept in the average, not smoothed away.