• 2.5 baseline — 0.6 × season 2.4 (12 gm) + 0.4 × last 10 2.6
• +0.3 opponent leak — they concede 64.2/game vs a 56.6 league average
• +0.6 at this ground — averages 3.1 there (12 gm)
• −0.5 wet forecast — averages 2 in the wet (5 gm)
• vs them: averages 2.5 over 6 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 19: 6 — far outside his usual range; kept in the average, not smoothed away.