• 10.0 baseline — 0.6 × season 10.4 (12 gm) + 0.4 × last 10 9.5
• −0.2 opponent leak — they concede 152.3/game vs a 155.4 league average
• −0.5 at this ground — averages 9.6 there (16 gm)
• vs them: averages 6.8 over 4 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.