Promoting him would seem to be the move, but he would seem to have a better opportunity with the Giants to put his own stamp on the defense since Daboll is an offense-oriented coach.
That said, despite what a bunch of you are saying, McDermott has a lot more job security than Daboll. And maybe Wink Martindale thought the same thing (re having freedom to operate) when he went to the Giants, but he learned pretty quickly that was not the case. If the Giants want him, it's probably going to come down to who Babich feels more comfortable working with. Hopefully that's McDermott.