• 4.5 baseline — 0.6 × season 4.8 (20 gm) + 0.4 × last 10 4.1
• −0.0 opponent leak — they concede 35.3/game vs a 35.3 league average
• −0.8 at this ground — averages 3.8 there (4 gm)
• vs them: averages 5.8 over 4 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.