• 0.5 baseline — 0.6 × season 0.5 (17 gm) + 0.4 × last 10 0.5
• −0.0 opponent leak — they concede 4/game vs a 4.2 league average
• +0.0 at this ground — averages 0.5 there (45 gm)
• vs them: averages 0.5 over 2 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 17: 2 — far outside his usual range; kept in the average, not smoothed away.