• 5.5 baseline — 0.6 × season 5.6 (8 gm) + 0.4 × last 10 5.3
• −0.6 opponent leak — they concede 83/game vs a 93.4 league average
• +1.7 at this ground — averages 7.2 there (6 gm)
• vs them: averages 5.8 over 8 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 2: 10 — far outside his usual range; kept in the average, not smoothed away.