He's probably the only starting QB that's hurt right now

So it's hard to tell how concerning it is. This is usually the best time for QBs. They've had rest and can't be hit in camp. But Stafford is dealing with something so they shut him down.

If this isn't a new injury then I'm not worried. He got an injection for it mid-season last year and still played well enough to win a Superbowl. But if it's a new injury... Then idk.