• 3.9 baseline — 0.6 × season 3.8 (12 gm) + 0.4 × last 10 3.9
• −0.3 opponent leak — they concede 87/game vs a 93.4 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• wet forecast: too thin to count (1 gm) — shown, adds nothing
• vs them: averages 4.0 over 1 game — 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 12: 8 — far outside his usual range; kept in the average, not smoothed away.