• 6.0 baseline — 0.6 × season 6.6 (5 gm) + 0.4 × last 10 5.1
• +0.3 opponent leak — they concede 225.5/game vs a 213.6 league average
• +0.2 at this ground — averages 6.2 there (6 gm)
• vs them: averages 5.7 over 6 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.