• 6.4 baseline — 0.6 × season 6.6 (16 gm) + 0.4 × last 10 6.1
• +1.7 opponent leak — they concede 117.8/game vs a 93.4 league average
• −0.6 at this ground — averages 5.8 there (48 gm)
• vs them: averages 4.5 over 10 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.