• 0.8 baseline — 0.6 × season 0.9 (20 gm) + 0.4 × last 10 0.5
• −0.1 opponent leak — they concede 32.7/game vs a 35.7 league average
• −0.8 at this ground — averages 0 there (5 gm)
• vs them: averages 0.0 over 1 game — 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.