• 3.7 baseline — 0.6 × season 3.5 (6 gm) + 0.4 × last 10 3.9
• −0.1 opponent leak — they concede 92/game vs a 93.4 league average
• +1.8 at this ground — averages 5.4 there (26 gm)
• vs them: averages 6.0 over 4 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.