• 1.2 baseline — 0.6 × season 1.3 (16 gm) + 0.4 × last 10 1.1
• −0.2 opponent leak — they concede 3.2/game vs a 3.9 league average
• −0.3 at this ground — averages 0.9 there (55 gm)
• vs them: averages 0.4 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 3: 5 — far outside his usual range; kept in the average, not smoothed away.