• 8.6 baseline — 0.6 × season 8.3 (15 gm) + 0.4 × last 10 9.0
• +0.5 opponent leak — they concede 225.5/game vs a 213.6 league average
• −1.7 at this ground — averages 6.9 there (40 gm)
• vs them: averages 7.0 over 8 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.