• 5.3 baseline — 0.6 × season 5.5 (20 gm) + 0.4 × last 10 5.1
• +0.3 opponent leak — they concede 224.7/game vs a 213.6 league average
• −0.4 at this ground — averages 4.9 there (11 gm)
• vs them: averages 6.0 over 1 game — 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 3: 9 — far outside his usual range; kept in the average, not smoothed away.