• 1.1 baseline — 0.6 × season 1.2 (19 gm) + 0.4 × last 10 1.1
• −0.1 opponent leak — they concede 53.9/game vs a 56.6 league average
• −0.2 at this ground — averages 0.9 there (18 gm)
• vs them: averages 1.5 over 2 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.