A change can begin with a simple move, a nudge.
A change, to be effective, shouldn't be a revolution, where you divide but never conquer the resistance. The resistance will always be there waiting for an opportunity.
I'm not sure who needs the nudge, is it Matthews or marner or can it come from the ranks?
Dubas isn't on the ice, but he can determine who is available to be on the ice.
Keefe can't determine who is available, but he can determine who gets the minutes, I think he can influence more than Dubas.