• 7.4 baseline — 0.6 × season 7.0 (19 gm) + 0.4 × last 10 8.0
• +0.4 opponent leak — they concede 164.6/game vs a 155.4 league average
• −0.3 at this ground — averages 7.1 there (36 gm)
• vs them: averages 7.8 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.