• 11.9 baseline — 0.6 × season 11.5 (19 gm) + 0.4 × last 10 12.5
• +0.1 opponent leak — they concede 157.2/game vs a 155.4 league average
• −0.4 at this ground — averages 11.5 there (4 gm)
• vs them: averages 12.0 over 6 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 13: 19 — far outside his usual range; kept in the average, not smoothed away.