There's a mandible, but I don't think it's shatter proof. I do think Davis will prove to be too much for Walsh, but I doubt he stops him early, especially with walsh' hometown crowd boosting him up. He'll be there to fight.
That's what I think too. Davis is the sort of fighter that turns up the heat before getting you out of there, not someone who swings for the fences in rounds 1 and 2 trying to go home early.
Walsh has a strong outside chance, he's improved a lot over the years and is fully ready for his chance.. he's a quality boxer and will at least give a good account of himself.