• 3.7 baseline — 0.6 × season 3.9 (8 gm) + 0.4 × last 10 3.5
• +0.0 opponent leak — they concede 157/game vs a 155.4 league average
• −1.0 at this ground — averages 2.8 there (8 gm)
• vs them: averages 3.6 over 11 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.