• 23.8 baseline — 0.6 × season 23.3 (20 gm) + 0.4 × last 10 24.6
• −0.6 opponent leak — they concede 360.2/game vs a 369 league average
• −6.3 at this ground — averages 17.4 there (25 gm)
• vs them: averages 12.3 over 3 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.