• 5.2 baseline — 0.6 × season 5.0 (11 gm) + 0.4 × last 10 5.4
• +0.0 opponent leak — they concede 345.7/game vs a 344.9 league average
• +1.2 at this ground — averages 6.4 there (5 gm)
• −1.0 wet forecast — averages 4.1 in the wet (8 gm)
• vs them: averages 5.1 over 10 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.