Let's assume they grab a rookie QB. Now you have someone who's familiar with Dennison's offense in camp to teach your vet, your project, and your rookie QB the system. If he completely sucks or if your rookie might get swiped from the PS you cut ties. Unless you think teaching 4 QBs, including 2 rookies, from scratch is a better option, where's the downside? There's not franchise QB floating around in FA, so no one else that you bring in is going to be the answer, either.