• 5.7 baseline — 0.6 × season 5.4 (20 gm) + 0.4 × last 10 6.2
• +0.5 opponent leak — they concede 101.3/game vs a 93.4 league average
• +0.1 at this ground — averages 5.8 there (26 gm)
• vs them: averages 6.3 over 9 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.