• 0.4 baseline — 0.6 × season 0.5 (13 gm) + 0.4 × last 10 0.3
• +0.1 opponent leak — they concede 14.9/game vs a 12.8 league average
• −0.2 at this ground — averages 0.2 there (29 gm)
• −0.2 wet forecast — averages 0.2 in the wet (10 gm)
• vs them: averages 0.2 over 6 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 1: 2 — far outside his usual range; kept in the average, not smoothed away.