I have a guess as to what they're doing there. Everyone is freaking out that Justin Fields looks ready to start, and Nagy is asking the QB people who he knows best and trusts to help him evaluate Fields so he doesnt get too carried away with enthusiasm, or be too slow and careful, and he wants outside opinions to temper his own.
And if Dalton was looking good and Fields like a rookie, he wouldn't need it.
I am going to guess that the reason these guys are here is because Fields is looking like he might ready or close to it, and Nagy wants to make sure he makes the decision correctly.