• 16.0 baseline — 0.6 × season 16.1 (20 gm) + 0.4 × last 10 15.9
• −0.9 opponent leak — they concede 201.8/game vs a 213.6 league average
• −5.4 at this ground — averages 10.6 there (73 gm)
• vs them: averages 9.3 over 9 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.