• 3.0 baseline — 0.6 × season 3.2 (13 gm) + 0.4 × last 10 2.7
• +0.1 opponent leak — they concede 33.5/game vs a 32.7 league average
• +0.9 at this ground — averages 3.9 there (8 gm)
• vs them: averages 6.0 over 2 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.