• 4.8 baseline — 0.6 × season 4.8 (19 gm) + 0.4 × last 10 4.7
• −0.1 opponent leak — they concede 54.9/game vs a 56.6 league average
• −0.4 at this ground — averages 4.4 there (26 gm)
• vs them: averages 4.0 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.