• 23.8 baseline — 0.6 × season 22.8 (20 gm) + 0.4 × last 10 25.3
• −0.3 opponent leak — they concede 364.1/game vs a 369 league average
• −8.3 at this ground — averages 15.5 there (13 gm)
• vs them: averages 15.7 over 7 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 1: 6 — far outside his usual range; kept in the average, not smoothed away.