So far this season, Marner is 3rd on the Leafs in scoring behind Nylander and Matthews. In terms of goals he is tied for fourth id Matt Knies with just 5.
John Tavares, the other member of the core-four has just one less point than Marner, but two more goals. If the Leafs are going to be forced to move on from one of them, perhaps Marner is the right fit. Nylander is a pending unrestricted free agent this summer, but he is playing the best hockey of his career at the moment.