• 5.2 baseline — 0.6 × season 5.0 (9 gm) + 0.4 × last 10 5.5
• −0.3 opponent leak — they concede 145.2/game vs a 155.4 league average
• −0.2 at this ground — averages 5 there (23 gm)
• vs them: averages 2.0 over 3 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: 13 — far outside his usual range; kept in the average, not smoothed away.