• 7.1 baseline — 0.6 × season 7.3 (14 gm) + 0.4 × last 10 6.9
• −0.0 opponent leak — they concede 544.7/game vs a 545.7 league average
• −1.3 at this ground — averages 5.8 there (57 gm)
• vs them: averages 3.0 over 5 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.