• 24.4 baseline — 0.6 × season 22.4 (14 gm) + 0.4 × last 10 27.3
• −1.5 opponent leak — they concede 322.9/game vs a 344.7 league average
• −3.2 at this ground — averages 21.2 there (5 gm)
• vs them: averages 26.9 over 8 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.