• 2.3 baseline — 0.6 × season 2.1 (20 gm) + 0.4 × last 10 2.4
• +0.2 opponent leak — they concede 39/game vs a 35.7 league average
• −0.8 at this ground — averages 1.5 there (25 gm)
• vs them: averages 2.0 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.