• 9.9 baseline — 0.6 × season 10.2 (18 gm) + 0.4 × last 10 9.5
• −0.2 opponent leak — they concede 209.2/game vs a 213.6 league average
• −1.6 at this ground — averages 8.3 there (20 gm)
• vs them: averages 8.3 over 3 games — evidence, never summed

Most signals here point under while you're on the over — worth reading the working above before you commit.

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.