• 5.8 baseline — 0.6 × season 6.1 (16 gm) + 0.4 × last 10 5.2
• −0.2 opponent leak — they concede 181.1/game vs a 185.9 league average
• +3.2 at this ground — averages 9 there (23 gm)
• vs them: averages 9.8 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.