• 22.2 baseline — 0.6 × season 21.1 (19 gm) + 0.4 × last 10 23.8
• +0.1 opponent leak — they concede 369.9/game vs a 369 league average
• −7.5 at this ground — averages 14.7 there (6 gm)
• vs them: averages 18.4 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.