• 4.5 baseline — 0.6 × season 4.6 (21 gm) + 0.4 × last 10 4.5
• −0.3 opponent leak — they concede 87.4/game vs a 92.6 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• +0.1 wet forecast — averages 4.6 in the wet (5 gm)
• vs them: averages 3.2 over 5 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.