Safe choice may be the right one at this point.
Hillary is imploding. The Comey non-referral has her in a tailspin, and I doubt she has the political skills to pull out of it. Trump just needs to look Presidential so most of the mushy middle finds him an acceptable alternative. Pence helps him I think in this regard.
She has sounded terrible in the clips being played of her audios from last night. Awful! Simply horrific!