• 1.4 baseline — 0.6 × season 1.4 (16 gm) + 0.4 × last 10 1.5
• +0.2 opponent leak — they concede 4.8/game vs a 4.1 league average
• −0.6 at this ground — averages 0.8 there (9 gm)
• vs them: averages 1.3 over 8 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 15: 4 — far outside his usual range; kept in the average, not smoothed away.