• 10.5 baseline — 0.6 × season 10.9 (16 gm) + 0.4 × last 10 9.9
• −0.7 opponent leak — they concede 345.4/game vs a 369 league average
• +2.2 at this ground — averages 12.6 there (14 gm)
• vs them: averages 14.0 over 6 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.