• 2.2 baseline — 0.6 × season 2.1 (20 gm) + 0.4 × last 10 2.2
• −0.0 opponent leak — they concede 154.7/game vs a 155.4 league average
• +0.6 at this ground — averages 2.7 there (92 gm)
• vs them: averages 2.8 over 15 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: 0 — far outside his usual range; kept in the average, not smoothed away.