• 37.2 baseline — 0.6 × season 32.3 (6 gm) + 0.4 × last 10 44.4
• −3.0 opponent leak — they concede 1550.3/game vs a 1687.8 league average
• +45.3 at this ground — averages 82.4 there (9 gm)
• vs them: averages 103.8 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.