• 2.4 baseline — 0.6 × season 2.4 (15 gm) + 0.4 × last 10 2.4
• −0.1 opponent leak — they concede 22.6/game vs a 23.6 league average
• +0.0 at this ground — averages 2.4 there (38 gm)
• +0.1 wet forecast — averages 2.5 in the wet (13 gm)
• vs them: averages 1.7 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.