• 14.8 baseline — 0.6 × season 15.0 (5 gm) + 0.4 × last 10 14.6
• +0.7 opponent leak — they concede 386.5/game vs a 369 league average
• +0.2 at this ground — averages 15 there (8 gm)

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.