• 2.1 baseline — 0.6 × season 2.0 (21 gm) + 0.4 × last 10 2.2
• +0.0 opponent leak — they concede 351.7/game vs a 344.9 league average
• +1.7 at this ground — averages 3.8 there (8 gm)
• vs them: averages 1.8 over 5 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 5: 5 — far outside his usual range; kept in the average, not smoothed away.