• 2.7 baseline — 0.6 × season 2.4 (15 gm) + 0.4 × last 10 3.1
• −0.1 opponent leak — they concede 54.9/game vs a 56.6 league average
• +2.6 at this ground — averages 5.3 there (92 gm)
• vs them: averages 4.1 over 8 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.