• 4.8 baseline — 0.6 × season 4.9 (11 gm) + 0.4 × last 10 4.6
• +0.5 opponent leak — they concede 104/game vs a 93.4 league average
• −0.1 at this ground — averages 4.7 there (21 gm)
• vs them: averages 3.0 over 2 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 20: 12 — far outside his usual range; kept in the average, not smoothed away.