• 6.0 baseline — 0.6 × season 6.1 (17 gm) + 0.4 × last 10 5.8
• +0.1 opponent leak — they concede 349.4/game vs a 344.7 league average
• −0.8 at this ground — averages 5.2 there (20 gm)
• vs them: averages 4.9 over 11 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.