• 1.0 baseline — 0.6 × season 1.0 (19 gm) + 0.4 × last 10 0.9
• −0.0 opponent leak — they concede 34.1/game vs a 35.7 league average
• +0.5 at this ground — averages 1.4 there (36 gm)
• +1.8 wet forecast — averages 2.8 in the wet (15 gm)
• vs them: averages 1.4 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.