Marner should be able to get things done with Gauthier as his center.
Saying he should have Tavares instead of Matthews as his center so that he can get stuff done is the weakest excuse I have ever heard.
He needs to start playing like the type of guy who can start making things happen regardless of what his team mates are doing. If you need other players to finish your work, and for them to be playing well in order for you to be effective, then you need to be a lot better. Regardless of how many points you put up. Tavares, Nylander and Matthews have all shown that they can take charge and win games regardless of how their team mates are doing. Heck even Hyman has done it more than a few times. Even when they do not always show up on the scoresheet, and even if they are not always consistenly putting up those efforts. Marner has not had many of those games where it looks like he is in the drivers seat, but rather has his effectiveness determined by how well Tavares, Matthews, Hyman, etc. play that game. That is simply not going to cut it at any point, but especially not in the playoffs when you are expected to be a top performing player for this team.