• 1.5 baseline — 0.6 × season 1.3 (19 gm) + 0.4 × last 10 1.8
• +0.2 opponent leak — they concede 27.1/game vs a 23.7 league average
• +1.0 at this ground — averages 2.5 there (8 gm)
• vs them: averages 2.5 over 4 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 11: 10 — far outside his usual range; kept in the average, not smoothed away.