• 1.4 baseline — 0.6 × season 1.4 (20 gm) + 0.4 × last 10 1.3
• +0.1 opponent leak — they concede 38.4/game vs a 35.7 league average
• +0.1 at this ground — averages 1.5 there (70 gm)
• vs them: averages 1.6 over 10 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: 4 — far outside his usual range; kept in the average, not smoothed away.