• 1.4 baseline — 0.6 × season 1.3 (17 gm) + 0.4 × last 10 1.5
• +0.2 opponent leak — they concede 64.2/game vs a 56.6 league average
• −0.0 at this ground — averages 1.4 there (87 gm)
• vs them: averages 0.5 over 12 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 12: 4 — far outside his usual range; kept in the average, not smoothed away.