• 4.6 baseline — 0.6 × season 4.2 (13 gm) + 0.4 × last 10 5.1
• −0.3 opponent leak — they concede 175.7/game vs a 185.9 league average
• −0.1 at this ground — averages 4.4 there (9 gm)
• vs them: averages 9.0 over 1 game — 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.