• 7.5 baseline — 0.6 × season 7.1 (19 gm) + 0.4 × last 10 8.0
• −0.3 opponent leak — they concede 148.3/game vs a 155.4 league average
• −0.7 at this ground — averages 6.7 there (15 gm)
• vs them: averages 5.3 over 4 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.