Somewhat disagree to some degree on Frazier. He has less than 200 career PA and has been ok vs LHP. high K rate, but pretty decent power. Hasn't been much of a defender though.
I wouldn't necessarily look at him as a starter, but would be a pretty good complementary piece to someone like Brantley starting in platoon situation.
Whether Newcomb for Gray and Frazier is something the Yankees would do...I don't really think so. I don't have a strong feeling for the Braves end, but I don't see a big downside. Frazier would be a better bench bat than they've had recently with a legit possibility to become a regular. Gray might give you something like Newcomb did and you certainly have other options.
I think though that the folks that want to move Newcomb aren't really honest with themselves. They want to move him because they don't think he is good enough, but they seem to want to believe that they are going to get great value back for him. Something about that calculation doesn't seem very realistic.
Something like this is a bit more realistic, but I think the Yankees probably would still look to get something more useful to them out of Frazier.