• 2.4 baseline — 0.6 × season 2.3 (19 gm) + 0.4 × last 10 2.6
• −0.4 opponent leak — they concede 26.6/game vs a 32.7 league average
• +0.8 at this ground — averages 3.2 there (37 gm)
• vs them: averages 4.0 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.