They all have their weaknesses.
Nylander is hardly a Selke candidate, and he doesn't play with one.
marner has been called Selke like, but isn't much of a goal scorer in the big games. Ranks 101st. in the past 5 playoffs (min 30 games).
Matthews is an all around player, who ranks 22nd. the past 5 years in goals per game, well below the elite goals scorers in the playoffs.
Back to the 4 Nations, if marner and Matthews are being asked to be their teams shutdown players, then that what their coach is after.
Canada and the other team have other goal scorers.
Just for S&G ...
For Nations:
Nylander +1
marner -2
Matthews +0