• 5.0 baseline — 0.6 × season 4.7 (16 gm) + 0.4 × last 10 5.5
• −0.0 opponent leak — they concede 93.2/game vs a 93.4 league average
• −0.2 at this ground — averages 4.8 there (10 gm)
• vs them: averages 5.5 over 4 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 9: 9 — far outside his usual range; kept in the average, not smoothed away.