• 32.1 baseline — 0.6 × season 31.6 (17 gm) + 0.4 × last 10 32.8
• +2.2 opponent leak — they concede 368.1/game vs a 344.7 league average
• +1.6 at this ground — averages 33.6 there (14 gm)
• vs them: averages 39.0 over 4 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.