• 7.1 baseline — 0.6 × season 7.1 (13 gm) + 0.4 × last 10 7.2
• +0.5 opponent leak — they concede 166.4/game vs a 155.4 league average
• −2.0 at this ground — averages 5.1 there (18 gm)
• vs them: averages 4.6 over 12 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.