• 1.3 baseline — 0.6 × season 1.2 (13 gm) + 0.4 × last 10 1.4
• +0.2 opponent leak — they concede 64.2/game vs a 56.6 league average
• +1.2 at this ground — averages 2.5 there (37 gm)
• vs them: averages 1.8 over 5 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 4: 5 — far outside his usual range; kept in the average, not smoothed away.