• 2.5 baseline — 0.6 × season 2.5 (14 gm) + 0.4 × last 10 2.6
• +0.0 opponent leak — they concede 57.5/game vs a 56.6 league average
• +0.6 at this ground — averages 3.1 there (75 gm)
• vs them: averages 2.9 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.