• 0.7 baseline — 0.6 × season 0.7 (9 gm) + 0.4 × last 10 0.7
• +0.2 opponent leak — they concede 12.3/game vs a 9.4 league average
• −0.2 at this ground — averages 0.5 there (25 gm)
• −0.5 wet forecast — averages 0.1 in the wet (7 gm)
• vs them: averages 0.7 over 7 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 4: 3 — far outside his usual range; kept in the average, not smoothed away.