• 3.5 baseline — 0.6 × season 3.6 (9 gm) + 0.4 × last 10 3.3
• −0.2 opponent leak — they concede 148.3/game vs a 155.4 league average
• −1.0 at this ground — averages 2.5 there (4 gm)
• vs them: averages 0.0 over 1 game — 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.