• 24.3 baseline — 0.6 × season 24.9 (20 gm) + 0.4 × last 10 23.4
• +3.1 opponent leak — they concede 39.8/game vs a 35.3 league average
• −4.3 at this ground — averages 20 there (53 gm)
• vs them: averages 16.8 over 6 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.