• 32.1 baseline — 0.6 × season 30.7 (16 gm) + 0.4 × last 10 34.2
• +1.8 opponent leak — they concede 389.2/game vs a 369 league average
• −9.1 at this ground — averages 23 there (11 gm)
• vs them: averages 24.7 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.