To be fair, Virtanen had 1 really good game and about 5 games where he was a complete non-factor and showed little.
That said, that one good game was impressive and I wouldn't have minded seeing more of him on the Horvat line for 9 games.
I'm not sure what being with Prust for 9 games is going to accomplish.
Well the goal he scored in his third was a "factor". I'll give you his first 2 games were "non factors" but since Game 3 he has looked stronger each game. The Sedin game was awkward but he was noticeable, the Edmonton game was very good, and last game (which I admit I missed) I hear he did well in a difficult position (4th line).
I'd look at his trendline more than just break his games into dichotomous "factor" or "non factor" games.