• 12.2 baseline — 0.6 × season 12.2 (14 gm) + 0.4 × last 10 12.3
• −0.8 opponent leak — they concede 200.3/game vs a 213.6 league average
• −2.2 at this ground — averages 10.1 there (74 gm)
• vs them: averages 10.6 over 10 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.