• 5.5 baseline — 0.6 × season 5.8 (18 gm) + 0.4 × last 10 5.2
• −0.4 opponent leak — they concede 87/game vs a 93.4 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing
• −0.3 wet forecast — averages 5.2 in the wet (14 gm)
• vs them: averages 5.2 over 9 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. Round 1: 13 — far outside his usual range; kept in the average, not smoothed away.