• 0.7 baseline — 0.6 × season 0.6 (19 gm) + 0.4 × last 10 0.7
• +0.1 opponent leak — they concede 11.4/game vs a 9.4 league average
• −0.1 at this ground — averages 0.6 there (36 gm)
• −0.1 wet forecast — averages 0.5 in the wet (15 gm)
• vs them: averages 0.6 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.