• 4.5 baseline — 0.6 × season 4.5 (20 gm) + 0.4 × last 10 4.6
• −0.2 opponent leak — they concede 150.3/game vs a 155.4 league average
• −0.8 at this ground — averages 3.8 there (34 gm)
• vs them: averages 5.7 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 16: 1 — far outside his usual range; kept in the average, not smoothed away.