• 5.0 baseline — 0.6 × season 5.3 (18 gm) + 0.4 × last 10 4.7
• +0.2 opponent leak — they concede 160.7/game vs a 155.4 league average
• −0.4 at this ground — averages 4.6 there (28 gm)
• vs them: averages 6.3 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 12: 13 — far outside his usual range; kept in the average, not smoothed away.