I don't agree with 13 but i do think he's worth as much as Auston. Matthews is the better scorer but Mitch makes everyone around him way better(just ask Tavares whom he would rather play with) and has a way better engine(kid barely looks tired out there) compared to Matthews and that's very important.
Statistics from the start of their careers show that Tavares and Matthews pretty much always make their linemates much better. For Mitch the statistics show that he sometimes makes his linemates somewhat better.