• 3.4 baseline — 0.6 × season 4.0 (19 gm) + 0.4 × last 10 2.4
• +0.3 opponent leak — they concede 25.6/game vs a 23.7 league average
• −0.4 at this ground — averages 3 there (4 gm)
• −2.0 wet forecast — averages 1.3 in the wet (9 gm)
• vs them: averages 4.0 over 8 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 10: 20 — far outside his usual range; kept in the average, not smoothed away.