• 10.2 baseline — 0.6 × season 10.3 (20 gm) + 0.4 × last 10 10.1
• +0.9 opponent leak — they concede 233.1/game vs a 213.6 league average
• +1.6 at this ground — averages 11.8 there (47 gm)
• +1.7 wet forecast — averages 11.9 in the wet (8 gm)
• vs them: averages 11.6 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.