• 13.9 baseline — 0.6 × season 13.7 (15 gm) + 0.4 × last 10 14.2
• +0.8 opponent leak — they concede 365.4/game vs a 344.9 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• vs them: averages 13.0 over 3 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 21: 28 — far outside his usual range; kept in the average, not smoothed away.