• 5.7 baseline — 0.6 × season 5.7 (10 gm) + 0.4 × last 10 5.7
• −0.3 opponent leak — they concede 201.8/game vs a 213.6 league average
• +1.6 at this ground — averages 7.3 there (88 gm)
• vs them: averages 7.6 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.