5v5 Marner is having one of his worst statistical years.
He's above his averages on the power play and with an empty net.
I dont think anyone would say this about a star player "Xxx coach is coming in, now watch their powerplay points crumble."
Also, Berube has frequently commented in postgames that cerrain players are being overly fancy, not playing a direct "north-south" game, and are not going to the net. He's said they cant be too fancy when specifically addressing the leafs top players. We know Tavares isnt fancy, and Matthews can be very N-S. So that leaves Marner and Nylander. Additionally, when recently asked about putting Nylander, Tavares Marner together - Berube specifically said they cant play fancy. Lastly, Berube has specifically responded to a reporters question regarding Marner having a net oresense and he responded we coach our players to always have two on the net.