• 3.6 baseline — 0.6 × season 3.8 (18 gm) + 0.4 × last 10 3.2
• −0.1 opponent leak — they concede 35.2/game vs a 35.7 league average
• −1.3 at this ground — averages 2.3 there (30 gm)
• vs them: averages 4.0 over 3 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.