That's one of the things that made the Hitmen so deadly. I've only watched a game or 2 myself, but the games I did, Virtanen was all over the place. Constantly in the puck carriers face, and forcing him to make a decision. If you hesitate too long, you know Virtanen is going to hurt you bad with a big check. It causes the other team to make quicker decisions, and of course, when you never have time to think, eventually you make the wrong one and then the Hitmen try to capitalize.
From what I can tell, Calgary uses their other seniors for more offensive roles, while Virtanen kind of plays a similar role to the likes of a defensive end in football. Constantly keeping the temp up and forcing the other team to make plays because he is such a constant threat both with his speed, and physicality, but also, you know every coach is telling their players, don't mess around when Virtanen is around you. Because if he gets a turnover, and a couple steps, he is gone, and that shot is deadly.