• 12.8 baseline — 0.6 × season 13.0 (19 gm) + 0.4 × last 10 12.5
• −0.1 opponent leak — they concede 211.2/game vs a 213.6 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing
• vs them: averages 8.7 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 6: 2 — far outside his usual range; kept in the average, not smoothed away.