• 4.3 baseline — 0.6 × season 4.1 (20 gm) + 0.4 × last 10 4.7
• −0.0 opponent leak — they concede 93.2/game vs a 93.4 league average
• +0.2 at this ground — averages 4.5 there (74 gm)
• vs them: averages 3.7 over 9 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: 12 — far outside his usual range; kept in the average, not smoothed away.