• 0.7 baseline — 0.6 × season 0.6 (19 gm) + 0.4 × last 10 0.8
• −0.2 opponent leak — they concede 16.2/game vs a 23.6 league average
• +1.3 at this ground — averages 2 there (4 gm)
• vs them: averages 1.5 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.