• 0.9 baseline — 0.6 × season 0.9 (10 gm) + 0.4 × last 10 0.9
• −0.0 opponent leak — they concede 35.4/game vs a 35.7 league average
• −0.4 at this ground — averages 0.5 there (29 gm)
• vs them: averages 0.0 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 21: 3 — far outside his usual range; kept in the average, not smoothed away.