• 119.0 baseline — 0.6 × season 119.8 (11 gm) + 0.4 × last 10 117.8
• −11.9 opponent leak — they concede 1519.7/game vs a 1687.8 league average
• −16.8 at this ground — averages 102.2 there (13 gm)
• vs them: averages 65.2 over 5 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.