• 16.3 baseline — 0.6 × season 19.4 (16 gm) + 0.4 × last 10 11.5
• −0.5 opponent leak — they concede 335/game vs a 344.9 league average
• +26.5 at this ground — averages 42.8 there (5 gm)
• vs them: averages 44.1 over 7 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.