• 0.5 baseline — 0.6 × season 0.5 (11 gm) + 0.4 × last 10 0.5
• +0.0 opponent leak — they concede 13.2/game vs a 12.8 league average
• −0.3 wet forecast — averages 0.2 in the wet (6 gm)
• vs them: averages 0.3 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.