Neither nash nor carter are playmakers in the truest sense and I think that's part of the reason that they haven't clicked with each other. Injuries also impacted carter's start.
I don't like either player's term, or trade cost.
Leafs need more help keeping pucks out of their own net then they do putting pucks in the other. A big, playmaking, centre sure would be nice, but what teams doesn't want/need one of those?