• 12.8 baseline — 0.6 × season 13.0 (18 gm) + 0.4 × last 10 12.6
• +1.2 opponent leak — they concede 1851.3/game vs a 1687.8 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• vs them: averages 22.6 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. Round 8: 47 — far outside his usual range; kept in the average, not smoothed away.