• 1.2 baseline — 0.6 × season 1.1 (19 gm) + 0.4 × last 10 1.4
• +0.2 opponent leak — they concede 10.8/game vs a 9.4 league average
• −0.6 at this ground — averages 0.7 there (6 gm)
• vs them: averages 0.7 over 7 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 12: 5 — far outside his usual range; kept in the average, not smoothed away.