• 3.2 baseline — 0.6 × season 3.1 (15 gm) + 0.4 × last 10 3.2
• +0.8 opponent leak — they concede 117.8/game vs a 93.4 league average
• +0.6 at this ground — averages 3.7 there (51 gm)
• vs them: averages 5.3 over 8 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.