Virtanen is a true power forward and is a straight up and down, score off the rush player. The defensemen in the NHL are much stronger and trucking through everybody will be much more of a challenge.
The one thing I question with Virtanen is his vision and hockey sense. Nothing worse than a player who as all the tools but skates like a bull with his head down, never looking up (Aka. David Booth), which is my worst fear with him.
He is a speedster though, which makes up for some of it. But speed and strength alone won't help a ton with in-zone offence.
Until I'm shown Virtanen has good vision and hockey sense, I have Ehlers and maybe even Nylander above him.