• 7.4 baseline — 0.6 × season 7.3 (20 gm) + 0.4 × last 10 7.4
• −0.7 opponent leak — they concede 141.4/game vs a 155.4 league average
• −1.1 at this ground — averages 6.3 there (27 gm)
• vs them: averages 3.0 over 2 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.