• 10.3 baseline — 0.6 × season 10.3 (12 gm) + 0.4 × last 10 10.2
• −0.3 opponent leak — they concede 207.8/game vs a 213.6 league average
• −2.6 at this ground — averages 7.7 there (17 gm)
• vs them: averages 6.0 over 1 game — 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.