• 23.3 baseline — 0.6 × season 22.8 (20 gm) + 0.4 × last 10 24.1
• +1.1 opponent leak — they concede 386.2/game vs a 369 league average
• −2.3 at this ground — averages 21 there (39 gm)
• vs them: averages 21.0 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.