He did the same with Rielly last year. Hated watching it.
Done the same with Nylander and Marner as well.
Marner responded wonderfully to his strategy and has become a spark for every line he has been on.
If Matthews feels he needs 21min toi to get his pts, maybe he should look at Sundin who had some of his best years getting sub 20toi. When you get the chance to play, you show up! Matthews crapped the bed v. Boston. No excuses. This is a guy who is supposed to be the next best thing to McDavid. He should be able to perform at a higher level than he did.
As for linemates he got to play with Nylander all year who is the Leafs 3rd or 4th most talented forward, so that's not bad.