• 5.8 baseline — 0.6 × season 5.4 (19 gm) + 0.4 × last 10 6.5
• −0.3 opponent leak — they concede 176.5/game vs a 185.9 league average
• −1.1 at this ground — averages 4.8 there (4 gm)
• vs them: averages 7.1 over 7 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.