• 3.0 baseline — 0.6 × season 3.0 (10 gm) + 0.4 × last 10 3.0
• +0.3 opponent leak — they concede 101.3/game vs a 93.4 league average
• +1.0 at this ground — averages 4 there (40 gm)
• vs them: averages 2.0 over 3 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: 8 — far outside his usual range; kept in the average, not smoothed away.