Vatrano can perform in the playoffs, he's fast and agitating and not easy to play against with his tendency to finish his checks. My biggest criticism would be that he gets undisciplined at times. That said he has been scoring for every team he's played for, as for the Ducks it's usually alongside pretty mediocre linemates.
With 50% retention he could put a team over the edge twice, with him on the 3rd line producing an additional 5 goals or so compared to your average 3rd liner in about 20 playoff games, and to me that's a pretty safe bet.
A 1st rounder from a team picking #28-32? Not enough, but if it was a more mediocre playoff team, perhaps that alone is enough. Ducks should be more intrested in winger prospects over late 1sts.