Week 1 is the least predictable week of the season and the market knows it. That doesn't make it unbettable — it makes it a different bet.
The case for unders
Early-season offenses are out of rhythm, playcalling is conservative, and nobody wants to show their real scheme in September. Timing-based passing attacks especially take a few weeks.
The case against overreacting
Everyone knows the above, so it's often priced in. If a total already looks low, the edge is gone and you're just paying for a popular opinion.
Where I actually look
Games with a new offensive coordinator on one side. Uncertainty is where numbers get soft, and soft numbers are the entire job.
This is a sample post — replace with your own take.