• 10.5 baseline — 0.6 × season 10.1 (16 gm) + 0.4 × last 10 11.2
• −0.1 opponent leak — they concede 364.1/game vs a 369 league average
• −1.0 at this ground — averages 9.5 there (10 gm)
• vs them: averages 10.5 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.