• 0.3 baseline — 0.6 × season 0.3 (16 gm) + 0.4 × last 10 0.4
• +0.0 opponent leak — they concede 25.6/game vs a 23.6 league average
• −0.3 at this ground — averages 0 there (4 gm)
• −0.3 wet forecast — averages 0 in the wet (12 gm)
• vs them: averages 0.0 over 11 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.