• 1.2 baseline — 0.6 × season 1.2 (9 gm) + 0.4 × last 10 1.1
• +0.1 opponent leak — they concede 101.3/game vs a 93.4 league average
• +1.2 at this ground — averages 2.3 there (70 gm)
• vs them: averages 2.8 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 2: 3 — far outside his usual range; kept in the average, not smoothed away.