• 5.8 baseline — 0.6 × season 5.8 (10 gm) + 0.4 × last 10 5.8
• +0.1 opponent leak — they concede 158.8/game vs a 155.4 league average
• +1.3 at this ground — averages 7.1 there (13 gm)
• vs them: averages 2.0 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 6: 13 — far outside his usual range; kept in the average, not smoothed away.