• 2.0 baseline — 0.6 × season 2.2 (20 gm) + 0.4 × last 10 1.6
• −0.1 opponent leak — they concede 22.6/game vs a 23.6 league average
• +0.1 at this ground — averages 2.1 there (35 gm)
• +0.2 wet forecast — averages 2.2 in the wet (13 gm)
• vs them: averages 2.3 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.