• 1.4 baseline — 0.6 × season 1.5 (19 gm) + 0.4 × last 10 1.4
• +0.1 opponent leak — they concede 13.5/game vs a 12.2 league average
• −0.5 at this ground — averages 1 there (49 gm)
• vs them: averages 1.3 over 4 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: 6 — far outside his usual range; kept in the average, not smoothed away.