• 0.6 baseline — 0.6 × season 0.6 (17 gm) + 0.4 × last 10 0.5
• −0.2 opponent leak — they concede 8.8/game vs a 12.2 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• −0.6 wet forecast — averages 0 in the wet (5 gm)
• vs them: averages 0.5 over 2 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 3: 3 — far outside his usual range; kept in the average, not smoothed away.