• 14.7 baseline — 0.6 × season 14.8 (13 gm) + 0.4 × last 10 14.5
• +0.8 opponent leak — they concede 389.2/game vs a 369 league average
• +0.4 at this ground — averages 15 there (29 gm)
• +4.6 wet forecast — averages 19.3 in the wet (10 gm)
• vs them: averages 18.0 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 6: 5 — far outside his usual range; kept in the average, not smoothed away.