Young defenders development is insanely rocky and up and down compared to comparable young forwards.
Marner and the other two youngsters help create the current identity of this team. I don't get the fascination with some on this board to trade from such a strength to create what many views as a more balanced team. Only 3 of the 8 teams left really have high-end number 1's (St Louis, Nashville, and Ottawa), most of the other teams have a balanced but strong defense's. Pitt is without Letang (who I've always thought is slightly overrated) and built around a quick transition defense. Anaheim has a good d but no true franchise all-around #1. Edmonton doesn't have a true number one, but Klefbom may be one. Carlson and McDonagh are number ones, but not on the elite end. We only really have one gaping hole in our top 4 and our defense is quite young. Just have faith in our drafting, development, and ability to navigate the FA market. I highly doubt anyone in the front office is considering moving Marner for a defender unless it's someone like Doughty. They aren't doing it for another young defender who's development tends to be rocky.